Industrial Ethernet - from the Office to the Machineschusterusa.com/.../harting_industrial_ethernet_handbook.pdf · 2013. 8. 27. · HARTING The best connections worldwide – because

Ronald Dietrich

Industrial Ethernet

... from the Office to the Machine - world wide -

Band I

Industrial Ethernet... from the Office to the machine - world wide -

HARTINGThe best connections worldwide – because quality connects.

HARTING was founded in 1945 by the family that still retains sole ownership of the company. HARTING presently employs more than 2 000 people including 150 highly qualified engineers and over 100 sales engineers who take care of the daily needs of our customers.

Today, HARTING is the leading manufacturer of connectors with 34 subsidiary companies in Europe, America and Asia.

As the market leader, HARTING offers the advantage of ‘just in time’ services. It is therefore no wonder that the company maintains close business relationships with all of its important customers active in the world market. HARTING is the market leader in several of its product sectors.

HARTING can draw on many years of extensive experience gained in achieving high degrees of protection in industrial environments (IP 65 and higher), all of which has flowed into expanding its product portfolio as well as the development of its family of devices for industrial communication.

HARTING products are manufactured utilizing cutting edge and efficient productions methods. CAD systems support research and development as well as tool making activities. We abide by our philosophy of quality, which states that only fully automatic manufacturing processes can achieve a zero error rate. In accordance with DIN EN ISO 9001, the organisation and procedures constituting our quality assurance measures are documented in a quality assurance manual.

HARTING employs approximately 60 members of staff in quality assurance. The majority of them are highly qualified engineers and technicians who have gained their qualifications through the German Society for Quality (DGQ) or the Swiss Association for Quality (SAQ).

Industrial Ethernet

Ronald Dietrich

... from the Office to the Machine - world wide -

This book was compiled with the technical support of HARTING Electric GmbH & Co. KG, Dezember 2004.

All rights reserved by HARTING Electric GmbH & Co. KG, D-32339 Espelkamp.

Author: Ronald Dietrich

Design and Layout: Ronald Dietrich

Translation: Scriptor GmbH, Bielefeld

Print and bookbinding: Printshop Meyer, Osnabrück

Pictures: Company photos

All other illustrations: HARTING Electric GmbH & Co. KG

All rights are reserved, especially relating to the translation, reprint and the extraction of illustration, broadcasting, the photo-mechanical or similar repro-duction and storage in data processing systems. This also applies to partial utilization. The reproduction of utility names, trade names, product designations etc. in this documentation does not, even if without special reference, manifest an assumed right to consider names in the sense of legal status for trademarks and trademark protection as being freely available to the public.

Important note

As a result of research and standardization technical findings are subject to continuous change. The author has exercised meticulous care to ensure that the information and statements in this documentation correspond with the current state-of-the-art. However, the user is not exempt from the obligation to check whether the information in this documentation deviates from the information contained in the original documentation (especially for standards) and to determine the utilization of this information under own responsibility.

DIN standards and other technical regulations

The DIN standards, VDE regulations and other technical regulations referred to in this documentation relate to the editions available at the time of copy deadline. Relevant for the user of a standard, however, is only the latest edition of the respective standard. DIN standards can be ordered from Beuth-Verlag, Burggrafenstr. 6, 10787 Berlin.

Printed on bleached cellulose, 100 % free from chlorine and acid.

Preface

Dear Reader, this book is intended to introduce you to the subject of Industrial Ethernet. At the same time, it seeks to demonstrate the possibilities open to you to fulfil your requirements for the industrial use of Ethernet by utilizing HARTING components. Following a short summary on the subject of fieldbus technology, we will describe the particular demands placed on Industrial Ethernet and how HARTING provides the appropriate solutions.

It is not the intention, nor can this book cover all questions relating to the subjects ‘fieldbus technology’ and ‘Industrial Ethernet’. For more detailed information on these subjects, please refer to the corresponding recommen-dations contained in the ‘Further reading’ list at the end of this book.

The standards and guidelines contained in this book were valid in 2004. Dear Reader, if by reading this book you should feel encouraged to take a more in-depth look at the subject of Industrial Ethernet or even put the knowledge gained into practise, you are duty-bound to ensure that you are aware of the latest information concerning prevailing law as well as the latest standards and guidelines. This book is intended to be an introduction to the subject of Industrial Ethernet. It was not written with the intention of providing a detailed description of standards and guidelines. Descriptions of individual devices and components contain no detailed reference to proprietary or patent rights.

Further information about HARTING devices and components described in this book are contained in the relevant catalogues and technical manuals. The sources where they can be drawn are contained at the end of this book.

Espelkamp, June, 2005

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Contents

Preface .....................................................................................................7

1 General Information about Fieldbus Technology ..........................131.1 Historical background ......................................................................... 131.2 The Automation pyramid .................................................................... 17

The field level ............................................................................... 17The control or process level ......................................................... 18The system or cell level ................................................................ 18The process control and the management levels ........................ 19

1.3 The Layer model ................................................................................. 19Layer 1: Physical Layer ................................................................ 20Layer 2: Data Link Layer .............................................................. 20Layer 3: Network Layer ................................................................ 21Layer 4: Transport Layer .............................................................. 21Layer 5: Session Layer ................................................................. 21Layer 6: Presentation Layer ......................................................... 21Layer 7: Application Layer ............................................................ 21Using the ISO/OSI Reference Model ........................................... 21

1.4 Classifying the fieldbus systems ......................................................... 22Fieldbus systems with decentralised master transfer ................... 23Fieldbus systems with central master transfer ............................. 24

1.5 Further information ............................................................................. 24

2 Industrial Ethernet ............................................................................252.1 What is Ethernet? ............................................................................... 252.2 Classic ‘Shared’ Ethernet ................................................................... 26

Ethernet and the ISO/OSI Reference Model ................................ 26The Ethernet address ................................................................... 28Standard Ethernet Frame ............................................................. 29Communication via Shared Ethernet ........................................... 30Broadcast telegrams .................................................................... 31Network Access Method CSMA/CD ............................................. 33Different approaches to improving performance .......................... 35Fast Ethernet ................................................................................ 35Gigabit Ethernet ........................................................................... 3610 Gigabit Ethernet ...................................................................... 38Ethernet with switching (Switched Ethernet) ................................ 39

2.3 Industrial Ethernet Network ................................................................ 40Why Ethernet for industry? ........................................................... 40Fields of applications for Industrial Ethernet ................................ 43General requirements placed on Industrial Ethernet networks .... 45User organisations and protocol variants ..................................... 49

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3 Transmission Technology and Cabling for Industrial Ethernet ...533.1 Network topologies ............................................................................. 55

Star ...............................................................................................55Tree ..............................................................................................55Line ...............................................................................................56Ring (redundancy) ........................................................................ 56

3.2 Active and passive network components ............................................ 573.3 Ethernet gateways .............................................................................. 583.4 Ethernet router .................................................................................... 593.5 Ethernet bridges ................................................................................. 603.6 Ethernet switches ............................................................................... 60

Switch – the key network component in Switched Ethernet ......... 60Operating modes .......................................................................... 61Ethernet switches with IP 20 protection ....................................... 64Ethernet switches with IP 65 / IP 67 protection for direct mounting .......................................................................................65‘In-between’ Ethernet switches for mounting onto external enclosure panels .......................................................................... 70

3.7 Ethernet hubs ..................................................................................... 74Hub as an active network component .......................................... 74Operating modes .......................................................................... 75Ethernet hubs with IP 20 protection ............................................. 75Ethernet hubs with IP 65 / IP 67 protection .................................. 76

3.8 Industrial Outlets for Industrial Ethernet ............................................. 81Industrial Outlet as a passive network component ....................... 81Industrial Outlets for wall mounting in industrial environments .... 82

3.9 Cabling ................................................................................................83Standardisation ............................................................................ 84Frequently used Ethernet transmission media ............................. 85Characterising cables and channels ............................................ 86Specifications for transmission cables made of copper for Industrial Ethernet ........................................................................ 88Hybrid cable ................................................................................. 90Special cable for Gigabit Ethernet ................................................ 90Special cable for 10 Gigabit Ethernet ........................................... 91Power on Ethernet (PoE) ............................................................. 91

3.10 Connectors ......................................................................................... 93Connectors for IP 20 .................................................................... 94Connector for IP 65 / IP 67 ........................................................... 94Hybrid connectors ........................................................................ 97Contact assignment ...................................................................... 98Special conditions for Gigabit Ethernet ...................................... 101

4 Future Prospects ............................................................................103

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5 Overview of Modules and Accessories for Ethernet Components from HARTING ................................................................................105

5.1 Ethernet devices – Overview of types .............................................. 105Ethernet switches for direct mounting ........................................ 106‘In-Between’ Ethernet switches .................................................. 106Ethernet hubs ............................................................................. 107Industrial Outlets ........................................................................ 107

5.2 Mounting options .............................................................................. 1085.3 Available cable types ........................................................................ 1085.4 Connectors ....................................................................................... 110

Annex A List of Standards and Guidelines .................................. 113A-1 Standards and guidelines applicable to Ethernet / bus technology .. 113

EN standards .............................................................................. 113IEEE standards .......................................................................... 114IEC standards ............................................................................. 115Guidelines .................................................................................. 115

A-2 Standards and guidelines for devices ............................................... 116EN standards .............................................................................. 116IEC standards ............................................................................. 117UL standards .............................................................................. 117

A-3 Standards and guidelines for connectors ......................................... 117EN Standards ............................................................................. 117IEC standards ............................................................................. 118

A-4 Standards and guidelines, general ................................................... 118EN standards .............................................................................. 118IEC standards ............................................................................. 118HD / VDE standards ................................................................... 118

Annex B Bibliography .................................................................... 119B.1 General information about fieldbus technology ................................ 119B-2 Industrial Ethernet / network technology ........................................... 120

Annex C Continuative Links ..........................................................121C-1 Links for field bus, general ............................................................... 121C-2 Links for Industrial Ethernet .............................................................. 121C-3 Other links .........................................................................................122

Glossary ..........................................................................................123

Degrees of Protection .........................................................................151

List of figures .......................................................................................155

List of tables ........................................................................................159

Index ..........................................................................................161

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131 General Information about Fieldbus Technology


1.1 Historical background

In the past, an alternative was sought to purely being able to enter and read data and signals directly at the machine or system; instead engineers also wanted to be able to provide data inputs and outputs as well as signal and status indicators to a remote control room. The first step in this direction was to connect the control room with each point at which measurements were taken at the machine.

As the possibilities for displaying and operating grew, so did the demands and requirements. Simply displaying status information became insufficient; it should also be possible to perform process control tasks from the control room. However, control of machines and systems as well as the detection of various statuses and measurement values requires the transmission of an enormous amount of data and signals. Each sensor and every measurement point was still being conventionally wired with various amounts of individual wires to a switching cabinet or central evaluating unit via marshalling cabinets. That meant that as well as the huge amount of cables and wires that sometimes needed to be routed across large distances, high standards were required with regard to the creation and adherence to wiring plans as well as the installation of the cables and wires. Nevertheless, the danger of wiring mistakes remained extremely high. Troubleshooting often proved to be quite difficult, because the errors on the individual wires could occur anywhere along the fairly long distances between the point of detection and the central switchgear cabinet. A further big handicap became apparent when alterations to the wiring were made necessary, for instance, when functions became superfluous or additional signals were required.

Figure 1-1 Cable installation based on conventional wiring

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Cable installation was simplified with the introduction of the fieldbus systems: fieldbus-compatible components were connected to the fieldbus directly at the machine or at the point of measurement. Only the fieldbus itself required a separate cable to the central switchgear cabinet or controller station.

As well as reducing the wiring needed to connect the field devices to the higher-level controller and systems, this simplification also led to a considerable reduction in the susceptibility to faults and associated troubleshooting. Only a fraction of the work is necessary when a component is no longer required, needs replacing or when a new component has to be installed: theoretically, as well as the connection to the existing fieldbus structure, an amendment to the corresponding configuration and parameter software is all that may be necessary.

Figure 1-2 Cable installation based on a fieldbus

Together with increasing automation and decentralisation in measurement, sensor and drive technologies, the need grew to create multi-vendor and open communication standards that would connect different devices from various manufactures as well as guarantee cross-system communication. At the same time, decentralised field devices, sensors and actuators continue to become available with improved functionality, so that communication increasingly has to flow in various directions:

• From the PLC (transmitter) to the field devices, sensors and actuators (receivers)

• From the field devices, sensors and actuators (transmitters) to the PLC (receiver)

• Between the field devices, sensors and actuators (alternatively acting as transmitters and receivers)

Due to stringent quality and safety requirements, importance is increasingly being placed on the transmission speed of the signals and messages with respect to maintaining certain requirements; these include, for example, diagnosis and troubleshooting, safety-relevant transmission of data, and they also include fast processes such as those necessary in the paper or food industry.

The share of distributed intelligence continues to grow. As a result, automation tasks are becoming increasingly complex with ever-greater amounts of data to be


transferred; at the same time, the demands for greater reliability of data transfers continue to grow. Demands on transmission rates have risen in the last few years due to the categorical explosion in the amount of data being transmitted as well as the increased complexity of the automation tasks. It is realistic for us to expect a sharp increase in these demands in the wake of the introduction of fieldbus systems into safety-relevant areas, and the introduction of Industrial Ethernet into the field of automation.

This trend will continue for the next few years, and, in the final analysis, will be reflected in the number of installed fieldbus stations, as well as in the share that fieldbus communication will have of automation activities as a whole.

With growing demands for a universal, harmonised data landscape as well as greater demands for the transfer of increasingly larger amounts of data together with continuously escalating transmission speeds, the classic fieldbus systems will eventually reach the limits of what they can do. That, however, does not mean that these fieldbus systems will be completely replaced. On the one hand, they are already in a position to fall back on many installations in industrial applications around the world. On the other hand, classic fieldbus systems are often already designed for rapid data transmissions. As a rule, they are only based on the layers 1 and 2, and possibly layer 7 of the OSI Reference Model (please refer to section 1.3 ‘The Layer Model’). Relatively young as far as industrial applications are concerned, Industrial Ethernet in the main also makes use of protocols for the higher layers 3 to 7 on top of its ‘pure’ Ethernet protocols of the layers 1 and 2, which in turn leads to a reduction of the effective rate of data transmission. For that reason, a realistic comparison between the classic field-bus systems and Industrial Ethernet cannot purely be based on the maximum possible rate of transmission, but rather has to take into consideration the transmission rate that can effectively be attained.

As the graphic below demonstrates, most classic fieldbus systems achieve transmission rates ranging between a few Kbit/s through to several Mbit/s. Industrial Ethernet is already in the starting blocks to achieve even higher rates of transmission up to as much as several Gbit/s.

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1kbit/s

9,6kbit/s

19,2kbit/s

60kbit/s

150kbit/s

500kbit/s

300kbit/s

1Mbit/s

10Mbit/s

100Mbit/s

1Gbit/s

10Gbit/s

DIN-Messbus

HART

BITBUS

ARCNET

INTERBUS

SERCOS

AS-Interface

CAN / CANopen

PROFIBUS-FMS

PROFIBUS-DP

Ethernet Fast Ethernet

Gigabit Ethernet

10 Gigabit Ethernet

Figure 1-3 Overview of transmission rates for various classic fieldbus systems and Industrial Ethernet

Further developments are awaited with an air of expectancy, in particular as far as Industrial Ethernet is concerned. Today already, the first tentative steps towards 10 Gigabit Ethernet are showing a great deal of promise. In particular in conjunction with Industrial Ethernet, the new transmission technologies, for example, fibre-optics or wireless applications, will play an increasingly important role when decisions for a new fieldbus system are being contemplated.


1.2 The Automation pyramid

Based on the amount and number of the required components, the information to be transmitted within the different levels of a system can be portrayed in the form of a pyramid:

Plant or factory Computer;CAD / CAM

Master Computer,PCS

Cell Computer,PLC, PC

PLC, CNC, NC

Controllers,

Multiplexer

Sensors,Actuators,

Number ofComponents

Amount ofdata

Sensor / Actuator level

Control or Process level

System orCell level

Processcontrol

level

Management level

Factory bus /Office Network

Process orCell bus Network

FieldbusNetwork

Figure 1-4 The automation pyramid

Bus systems provide the means for communication both within and between the different individual levels. That said, the following applies: the higher the level is, the slower the rate of transmission, but the greater the amount of data that can be transmitted.

Standard Ethernet is used mainly for communication between the higher levels (from the management level to the system or cell level).

Bus systems used within and between the sensor/actuator level, the control level and the system/cell level are the classic fieldbus systems (PROFIBUS, AS-Interface, CAN, DeviceNet ...) and increasingly in the recent past, Industrial Ethernet.

The field level

This is the lowest level, where sensors and actuators are used to control production and manufacturing processes. Process-related data is for example:

• Analogue signals:• Liquid level, pressure, temperature, flow rate, rotational speeds, …

• Digital signals:• End positions, control states, …

This data is read-in at the field level and then processed. In addition to the normal process data, safety- and quality-relevant data is also read-in, processed and transmitted. This includes alarm values, run times, analysis values and so forth.

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Data exchange takes place predominantly between different levels, and only seldom between the devices within the same level. For example, setpoint values are transmitted from, and actual measured values are transmitted to a higher-level controller. However, although this controller can be located in the field level, it is generally assigned to the next level higher up – the control or process level.

The control or process level

The tasks covered by this level include:

• Collecting, conditioning and processing the data received from the assigned sensors and actuators on the field level

• Administering several control and regulating modules• Carrying out automation and control tasks• Routing selected data to the system level• Visual display of data• ...

Typical devices for this level are, for example, programmable logic controllers (PLC) and regulators or CNC modules.

Data exchange takes place both between and within the levels. For example, setpoint values can be transmitted from a higher-level controller to the lower-level sensors and actuators as can evaluation results be transmitted to the system or cell level. This data can equally be transmitted between the individual PLC modules within this level.

The system or cell level

This level is responsible for the monitoring, control and regulation of several processes. The tasks covered by this level include:

• Collecting, conditioning and processing the data received from the assigned controllers and regulators in the control level.

• Administering several control and regulating modules• Carrying out higher-level automation and control tasks• Routing certain data to the process control level• Central point for visualisation of selected data.• ...

Typical devices for this level are, for example, programmable logic controllers (PLC) and PCs.

Data exchange takes place both between and within the levels. For example, setpoint values can be transmitted from a higher-level management system to the lower-level PLCs and the evaluation results transmitted back to the management level. This data can equally be transmitted between the individual stations within this level.


The process control and the management levels

These two levels serve predominantly to control larger systems or factory operating areas as well as higher-level planning and control of the entire production. Standard Ethernet is generally the bus system used.

These two levels are of less relevance as far as classic fieldbus systems are concerned. Gateways operating as converters between the classic fieldbus systems and Standard Ethernet are normally utilized to enable communication between the lower levels and these two higher levels.

When contemplating Industrial Ethernet, these two levels are of interest to the extent that data exchange can take place through to the field level using Standard Ethernet / Industrial Ethernet..

1.3 The Layer model

The ‘Open Systems Interconnection Reference Model’ (abbrev. OSI Model, also often referred to as the ISO/OSI Reference Model) came into being in 1983 based on the experienced gained from using and developing Ethernet TCP/IP as a standard for office communication.

This reference model provides an extremely abstract description of the OSI environment. At least two open systems make up the OSI environment, these being connected to one another by means of a physical medium for the exchange of data. Having said that, each of these systems is an autonomous entity that can independently process and transmit data.

According to OSI specifications, data exchange takes place in an open system in accordance with formal rules of communication, which were developed in accordance with the ISO/OSI Reference Model.

In order to be able to use the ISO/OSI Reference Model on a system, the system needs to be divided up into two categories.

For using the ISO/OSI-Reference model on a system this system has to be splitted into two parts:

• In data processing to perform a certain task

and

• In the communication system solely responsible for the transfer of data.

The rules applied to the system of communication are called protocols. These rules require the exchange of data between the individual stations participating in this communication by means of messages that can be subdivided into four different types:

• Request• Indication• Response• Confirmation

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The ISO/OSI Reference Model is divided up into 7 layers. Each layer contains at least one instance specifying particular network functions. This instance can be compared with an independently functioning software module that carries out special tasks with the assistance of neighbouring instances.

2.

1.

3.

4.

5.

6.

7.

Application Program

Physical Transmission Medium

Application Layer

Presentation Layer

Session Layer

Transport Layer

Network Layer

Data Link Layer

Physical Layer

TransmissionProtocol

Higher Protocol

application-oriented layers

transport-oriented layers

Figure 1-5 ISO/OSI Reference Model

The tasks and functions are assigned to the individual layers as follows:

Layer 1: Physical Layer

Layer 1 (bit transmission layer) manages the physical medium for transmitting the individual bits of the telegram messages. This includes defining the transmitting medium (electrical cable, fibre-optics), connector assignment, type of modulation, transmission rate, and signal level as well as further physical parameters such as the length of cable and similar.

Layer 2: Data Link Layer

Layer 2 is responsible for the bus access procedure as well as the fail-safe transmission of blocks of data from the transmitter to a receiver (‘unicast’) or several receivers within a group (‘multicast’) or to all receivers (‘broadcast’).


Layer 3: Network Layer

Layer 3 supports the search and use of suitable transmission routes between the transmitter and receiver through the network, possibly via a communication PC.

Layer 4: Transport Layer

Layer 4 is responsible for the control of and error-free logical delivery of telegrams.

Layer 5: Session Layer

Layer 5 (communication layer) establishes, manages, synchronises and terminates communication between the participating stations of a bus communication.

Layer 6: Presentation Layer

Layer 6 is responsible for character coding and conversion of data, monitor and file formats into a suitably readable format for the corresponding computer.

Layer 7: Application Layer

Layer 7 provides interactive services (for example writing and reading) for other network Stations. In doing so, it provides an interface to the user programmes in PLC, PC and control systems.

Using the ISO/OSI Reference Model

Layers 1 to 4 are responsible for the transmission of data between the stations within the network. Layers 5 to 7 coordinate the interaction between the bus system and the user program of the computer in the respective station.

The structure of the layers applies only to the internal sequence of communication. It has nothing to do with the control levels of automation engineering.

Generally speaking, only the layers 1, 2 and 7 need be considered for the purpose of industrial communication by means of fieldbus systems. In order to increase the efficiency of the respective protocols and achieve faster transmission speeds, these layers are reduced even further in some individual fieldbus systems (for example, PROFIBUS-DP or AS-Interface).

The following image depicts a typical route taken by a message from the transmitter to the receiver utilising a fieldbus:

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Application Layer

Presentation Layer

Session Layer

Transport Layer

Network Layer

Data Link Layer

Physical Layer

Application Layer

Presentation Layer

Session Layer

Transport Layer

Network Layer

Data Link Layer

Physical Layer

Physikal Transmission Medium

supported layers

non-supported layers

Transmitter Receiver

Figure 1-6 Example of message transmission utilising a fieldbus in accordance with the

ISO/OSI Reference Model

1.4 Classifying the fieldbus systems

Based on Time Division Multiplex technology, ‘classic’ fieldbus systems are generally serial in nature. That means that the communicating partners must divide the transmitting time between themselves, because only one station can occupy the bus for transmission purposes at any given time.

For that reason, only fieldbus systems will be considered in the following that work with time division multiplexing.

Classification of the fieldbus systems can be carried out according to various aspects:

• According to access procedures or• According to topology

There are various options available to portray the association between the fieldbus systems and the various aspects. One variation is shown in the graphic below:


Line Topology Ring TopologyDeterministicMaster Transfer

RandomBus Access

Central MasterTransfer

Time Division

Decentralised MasterTransfer

Figure 1-7 Classifying the fieldbus systems

Fieldbus systems with decentralised master transfer

The master function of a bus system employing a decentralised master transfer mechanism is distributed between several stations. In this case, a distinction is drawn between the differing access mechanisms:

Deterministic bus access

Certain stations, known as the masters, are each permitted to transmit (token holders) for a defined period. Once this defined time has elapsed the token providing the necessary authority to transmit is passed on to the next master, which in turn becomes the active master. A logical ring is built up between the masters so that this process can be applied independently of the network topology. This process is known as ‘Token Passing’.

Typical fieldbus systems that function according to this principle include, amongst others, PROFIBUS and its variants.

Random bus access

Bus access is not granted according to a rigid predefined plan. That means that all stations have the same rights and are always ready to receive messages. Where necessary, they can begin to transmit messages when the bus is not occupied. The access procedure used is called CSMA (Carrier Sense Multiple Access).

The advantage of this access procedure is the possibility of event-controlled communication.

Typical fieldbus systems that function according to this principle are:

• CANopen / DeviceNet (CSMA/CA)• Industrial Ethernet (CSMA/CD)

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Fieldbus systems with central master transfer

In a bus system operating a centralised master transfer mechanism the master transfer function is carried out by a station defined as the master terminal. The master terminal cyclically queries all of the other network stations (slaves). The slaves are only permitted to transmit information following a request from the master.

With this form of data transfer, a distinction is drawn between the different topologies:

Line topology

Several stations are connected to a bus trunk cable by means of a stub line. Tree topology is an extended form of the line topology. The maximum length of such a cable is restricted by its electrical characteristics.

AS-interface is one of the typical fieldbus systems that make use of a line topology.

Ring topology

Both ends of the trunk cable forming the bus system are connected to each other. That is the reason why no line termination is required. The individual stations form a ring configuration. For data exchange purposes, separate data telegrams from each station as well as accumulated frame telegrams are used in the transmission of master information. The accumulated frame telegrams contain data for all of the stations. Each station receives the data addressed to him, and attaches its own data to this telegram at a time determined by the master.

INTERBUS is a typical fieldbus system that makes use of a ring topology.

1.5 Further information

It has of course not been possible with these descriptions to cover the entire subject of ‘Fieldbus Technology’ in great depth. That would go far beyond the scope of this chapter. After all, numerous books have already been published about the individual types of fieldbus, describing the corresponding basic information and technical possibilities. Further information is not only available in specialized literature but also in the appropriate guidelines and standards, which have been and will be published on this subject, as well as over the Internet. In that respect, it is particularly worth mentioning the individual user organisations, for example, PROFIBUS, CAN, DeviceNet, INTERBUS, and IAONA. Some addresses are listed in the Appendix.

252 Industrial Ethernet


2.1 What is Ethernet?

Ethernet is a relatively old standard originally developed by Xerox in 1975 for the serial transmission of data.

Ethernet is based on a concept by Dr Robert Metcalfe dating from 1973 describing the transfer of data between several networked stations connect by a coaxial cable.

Figure 2-1 Ethernet – The idea

The first attempts at transferring data between network stations able to act independently of one another were co-ordinated at an early stage by the IEEE (Institute of Electrical and Electronics Engineers). The Ethernet was standardised in the IEEE 802 in the 1980s, since when it has been extended many times. The ‘classic’ Ethernet was specified for a data transmission rate of 10 Mbit/s over a maximum distance of 2500 m (divided up into 5 segments of 500 m) and a maximum of 1024 network stations.

Since the 1990s, Ethernet has undergone a series of further developments in the following areas:

• Transmission media• Fibre optics• Wireless technology

• Data transmission rates• Fast Ethernet 100 Mbit/s (1995)• Gigabit Ethernet 1 Gbit/s (1999)• 10 Gigabit Ethernet (at the planning stage)

• Network topologies• Switched Ethernet

• Industrial Ethernet

Increasingly gaining in importance in the field of industrial automation, Ethernet today is the most prevalent base technology used in commercial EDP systems around the globe. The Ethernet protocol is embedded almost in full onboard inexpensive controller chips, so, together with wide distribution (or probably because of it) and the associated availability, Ethernet represents an economic solution for the construction of network connections.

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Today, there is hardly an alternative to Ethernet, especially when fast transmissions of large amounts of data are required.

Utilising Ethernet in both office and industrial environments achieves a homogeneous and standardised infrastructure for communication – extending smoothly from the office to the machine.

New milestones in the utilisation of Ethernet are being set with the arrival of new technologies for Gigabit Ethernet and 10 Gigabit Ethernet as well as the introduction of fibre-optics and wireless technology. It is precisely these new features that are providing the springboard for the growing use of Ethernet in industry.

Ethernet10 Mbit/s

Fast Ethernet100 Mbit/s

10 Gigabit Ethernet10 000 Mbit/s

Gigabit Ethernet1 000 Mbit/s

2004198519801973 1990 1995 2000

Idea,standardisation

Firstapplications

Standardproducts

Figure 2-2 Development of Ethernet to date

2.2 Classic ‘Shared’ Ethernet

Ethernet and the ISO/OSI Reference Model

Specified in the standard IEEE 802.1 to 802.3, Ethernet performs services provided by layers 1 and 2 of the ISO/OSI Reference Model. All incoming telegrams are filtered in layer 2, which basically means only the ‘right’ telegrams are passed onto the higher layers.

The transmission protocol is implemented in layer 3. The best-known protocol in conjunction with Ethernet is the Internet Protocol IP.

The transmission protocols are contained in layer 4. Ethernet is often used in conjunction with TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).


Higher-level tasks are achieved through various application protocols (FTP or SNMP) as well as by utilising special purpose protocols (for example, for automation). However, automation protocols can also be used to either extend the layers 3 or 4 or both, or even replace them entirely.

2.

1.

3.

4.

5.

6.

7. Application Layer

Presentation Layer

Session Layer

Transport Layer

Network Layer

Data Link Layer

Physical Layer

TCP / UDP

IP

CSMA/CD

Ethernet

Transmission Protocol

Higher Protocol



Application Protocols

OSI Reference model Ethernet layers

Figure 2-3 Ethernet and the ISO/OSI Reference Model

Layer 1

Layer 1 is responsible for unsecured transmissions via the physical medium, with data being transmitted bit-by-bit. The format of the Ethernet data package (‘frame’) to be transmitted is defined in the standard IEEE 802.3 (please refer to the section ‘Standard Ethernet Frame’ in this chapter).

Originally, the transmission medium used was copper coaxial cable. Today, copper cables are predominantly in use in the form of twisted pair cables. In the recent past, the use of fibre optic cables or wireless transmissions has grown increasingly.

Layer 2

As well as allocating access rights to the physical medium, this layer is concerned with the fail-safe transfer of blocks of data bits between two directly linked network stations. Access to the physical medium itself is regulated by CSMA/CD (Carrier Sense Multiple Access/Collision Detection) specifications in accordance with IEEE 802.3; please refer to the section ‘Network Access Method CSMA/CD’ in this chapter.

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Layer 3

Layer 3 implements the protocol responsible for managing the network layer of the ISO/OSI Reference Models. In the main, this Internet protocol is tasked with providing solutions for the following:

• Regulating problems of routing throughout the network• Generating associated with virtual connections via a physical medium• Introducing measures for network coupling

The Internet Protocol IP is the most widely known protocol throughout the Ethernet world.

Layer 4

This level controls the error-free flow of data in the correct sequence between the communicating network stations. Ethernet is often utilized with TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).

TCP is a connection-based protocol responsible for the error-free transmission of data; it is mostly utilized for transferring large amounts of data.

UDP is a connectionless protocol particularly suitable for fast, cyclic data traffic. Transmissions using UDP protocols are generally faster, however errors are not fixed.

Layers 5 to 7

The higher-level layers 5 to 7 specify the application protocols that allow the data being transmitted to be interpreted. There is already a wide spectrum of specified application protocols available for office applications (for example, FTP, http and others).

For industrial communications, there are presently various protocols in use that are incompatible with one another (please refer to the section ‘The Industrial Ethernet Network’ in this chapter).

The Ethernet address

As is the case with all mechanisms for transmissions between stations on a (local) network, each station on an Ethernet network requires a unique, assignable address. In the case of Ethernet, this station address is often called the MAC address (Medium Access Control address). Generally stored in a non-volatile memory, the MAC address is assigned to the physical network interface of the station by the manufacturer.

The Ethernet address always comprises six bytes, which are split up into two groups of three bytes respectively.

• The first group contains the address type (bits D47 and D46) as well as the vendor ID. The IEEE manages these IDs centrally, to guarantee that each Ethernet address remains unique all over the world.


• The second group contains a sequential serial number for the network interface.

D47 D45 ... D24D46 D23 ... D00

Address type Vendor address Serial number

Group 1 Group 2

Figure 2-4 Structure of a MAC address

The significance of the bits D46 and D47 depends upon the address type (destination or source address):

Address type

D47 D46Value Meaning Value Meaning

Destination address

0 individual address 0 This address is administrated globally by IEEE, meaning it is unique throughout the world.

1 Group address (for broadcast or multicast telegrams)

1 This address is administrated locally, meaning it is not co-ordinated through the IEEE.

Source address

0 always set to „0“ 0 This address is administrated globally by IEEE, meaning it is unique throughout the world.

1 1 This address is administrated locally, meaning it is not co-ordinated through the IEEE.

Table 2-1 Overview of address types

If the bit D46 is set to ‘1’, private networks without public access can be implemented using random address assignment. The IEEE does not co-ordinate the addresses of these networks. That means it is the vendor’s responsibility to ensure ‘unambiguous’ address administration.

Standard Ethernet Frame

The data transmission is realised on Ethernet by means of so-called data packets (‘frames’). These frames include a header and a check-sum, additional to the real user data.

Standard Ethernet frames are made up of six blocks:

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Block Size (bytes)

MeaningDesignation acc. to IEEE 802.3Preamble 8 bytes Tasked with synchronisation of the receiver as

well as indicate the start of the Ethernet frame.

Destination 6 bytes Address of the receiver

Source 6 bytes Address of the source

Type Field 2 bytes Indicates the type of protocol (for example, TCP/IP)

Data Field 46 to 1500 bytes

Data being transferred

Check 4 bytes CRC value (Cyclical Redundancy Check) to monitor transmission errors

Table 2-2 Standard Ethernet frame

Preamble Destination Source Type Field Data Field Check

8 bytes 6 bytes 6 bytes 2 bytes 46 - 1500 bytes 4 bytes

Figure 2-5 Standard Ethernet Frame

The ‘preamble’ block comprises 7 bytes for the actual preamble and 1 byte as ‘starting frame delimiter’. The start byte indicates to the receiver that the actual information part of the frame is about to begin.

The subsequent bytes contain the destination and source addresses. Additionally, the destination address is evaluated in the address filter of the Ethernet controller. Only frames containing the correct destination address are forwarded to the actual communication software.

Thus, each frame consists of 26 protocol bytes and between 46 and 1500 bytes of ‘user data’. A minimum of 46 bytes of user data achieves a frame length that can guarantee a faultless resolution of collision conditions. If less than 46 bytes of user data are available, the Ethernet controller automatically compensates for missing bytes by adding so-called ‘padding bytes’ to bring the frame up to this minimum size.

Whereas the protocol bytes correspond to defined patterns, the user bytes are not subjected to any restrictions. The only condition user bytes are subjected to is that they must be complete bytes (multiples of 8 bits).

Communication via Shared Ethernet

Ethernet was planned as a logical bus system: a transmitting network station is ‘heard’ by all other stations on the network. With its Ethernet controller, each Ethernet component filters out the telegrams intended for him. However, only telegrams with the correct destination address are accepted. It ignores all other telegrams.

The so-called broadcast or multicast telegrams are the exception.


Ethernet Hub

Station B

Receiverfilter

Trans-mitter

Station C

Receiverfilter

Trans-mitter

Transmitting to station C

Station D

Receiverfilter

Trans-mitter

Station A

Receiverfilter

Trans-mitter

Figure 2-6 Path taken by an Ethernet telegram

In figure 2-6, station A transmits a telegram to station C. This telegram is ‘heard’ by all stations but only accepted by station C.

The accepted telegrams are subsequently passed onto the higher layers in the communications software (for example, IP or TCP / UDP).

The receiver checks all telegrams destined for him for errors (check sum, length, format and so forth). Faulty telegrams are ignored. However, the receiver does not transmit an acknowledgement of receipt; thus, the transmitter has no way of knowing if its telegram has reached its destination without any faults.

Broadcast telegrams

Broadcast telegrams are Ethernet telegrams that are received by all stations on an Ethernet network.

Ethernet stations recognise a broadcast telegram by the fact that all bits of the destination address are set to ‘1’.

Ethernet HubBroadcast telegram

Station B

Receiverfilter

Trans-mitter

Station C

Receiverfilter

Trans-mitter

Station D

Receiverfilter

Trans-mitter

Station A

Receiverfilter

Trans-mitter

Figure 2-7 Path taken by broadcast telegrams

In figure 2-7, station B transmits a broadcast telegram that is ‘heard’ and accepted by all stations.

The so-called ‘jam signal’ is one example of a broadcast telegram transmitted by a station when it recognises a collision (please refer to the section ‘Network Access Method CSMA/CD’ in this chapter).

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Multicast telegrams

Multicast telegrams are directed to a group of receivers. A station can belong to a number of groups.

In the case of multicast, the following types of groups are differentiated:

• One-to-many A single transmitter transmits to a number of receivers.• Many-to-many A number of transmitters transmit to a number of receivers.• Many-to-one A number of transmitters transmit to a single receiver.

The transmitter can, but need not, belong to the group or respective receivers.

Ethernet stations recognise a multicast telegram by the fact that bit D47 of the destination address is set to ‘1’. Bit D31 is subsequently checked. The telegram is recognised as a broadcast telegram if this bit is also set to ‘1’. The telegram is recognised as a multicast telegram if the bit D31 is set to ‘0’. In this case, the bits D30 to D00 determine the group identification.

Multicast telegrams destined for unique group addresses around the world are a special case. These addresses are identified by bit D46 being set to ‘0’. These addresses are assigned centrally by the IEEE.

Further information on the subject Addresses is contained in the section below.

Ethernet HubMulticast telegramGroup 1

Station B

Receiverfilter

Trans-mitter

Station C

Receiverfilter

Trans-mitter

Station D

Receiverfilter

Trans-mitter

Station A

Receiverfilter

Trans-mitter

Figure 2-8 Path taken by multicast telegrams (group 1)

In figure 2-8, the station B transmits a multicast telegram to all other stations belonging to group 1. Stations A and D belong to this group.

All other stations ignore this telegram.

Ethernet HubMulticast telegramGroup 2

Station B

Receiverfilter

Trans-mitter

Station C

Receiverfilter

Trans-mitter

Station D

Receiverfilter

Trans-mitter

Station A

Receiverfilter

Trans-mitter

Figure 2-9 Path taken by multicast telegrams (group 2)


In figure 2-9, station B transmits a multicast telegram to all stations belonging to group 2. Stations A, B and C belong to this group. That means station A belongs to both group 1 and group 2. The transmitting station B belongs to the group of receivers.

All other stations ignore this telegram.

Network Access Method CSMA/CD

In a ‘classic’ Ethernet network, often called Shared Ethernet, all stations on the network share a so-called collision domain. All networked stations have the same rights. Thus, each station can attempt to transmit data at any time.

The control of Ethernet network access is regulated by the CSMA/CD method (Carrier Sense Multiple Access with Collision Detection).

Using ‘Carrier Sense’ logic, network components wishing to transmit data first check if the network is free. If it is, transmissions can begin. ‘Collision Detection’ checks are made at the same time to ascertain if other components have also began to transmit. If that is the case, a collision will occur. If a transmitting station recognises a collision, it curtails transmissions and transmits a so-called ‘jam signal’. Consisting of 4 to 6 bytes with the address ‘FF’ (all bits belonging to this signal are set to ‘1’) this signal is transmitted as a broadcast telegram, which means it will be ‘heard’ by all other network stations. As a result, all participating network stations stop transmitting and wait a randomly determined time before resuming transmissions.

The flow chart below offers a schematic outline of the data transmission process:

Stationwants to transmit

Listeningto the network

Networkfree ?

Transmit data andlisten to network

Collision ?

Data transmittedcorrectly

TransmitJam signal

Waiting inaccordance withback-off strategy

No

No

Yes

Yes

Figure 2-10 Sequence of a data transmission with CSMA/CD

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Classic Ethernet (transmission speed 10 Mbit/s) was designed to ensure a maximum signal propagation time of 25.6 µs between the two stations furthest apart. That means the first station to transmit can recognise a collision within max. 51.2 µs. This time is also known as the collision window. If no collision is recognised during this time, in other words, no jam signal was received, then the transmission has been completed successfully.

0

51,2 µs **25,6 µs *

ttime in µs

Networkstation n

Networkstation 1

Collisionrecognised

Figure 2-11 Schematic portrayal of the CSMA/CD method

* Maximum signal propagation time between the stations furthest apart

** Collision window Network station 1 begins to transmit Network station n (station furthest away) begins to transmit The telegram from network station 1 reaches network station n (maximum signal propagation time) which recognises a collision of data; it aborts transmissions and broadcasts a jam signal. Network station 1 recognises that the other network station has attempted to transmit data, meaning, that station 1 also recognises that its transmission has failed, and attempts to transmit again following a randomly determined amount of time.

Due to these collision characteristics, transmission times for frames depend largely on the workload of the network, and cannot be determined before hand. The more collisions occur, the ‘slower’ the entire network will be. Therefore, Shared Ethernet is not entirely suitable for industrial automation.

The maximum propagation time for data packets depends on the data transmission rate being used (for example at 10 Mbit/s: 25.6 µs, see above). For its part, the propagation time determines the maximum possible size of the Ethernet network:

Type of Ethernet

Transmission rate Collision window Maximum length of transmission path *

Shared Ethernet 10 Mbit/s 51.2 µs > 100 m / 500 m **

Fast Ethernet 100 Mbit/s 5.12 µs 100 m

Gigabit Ethernet 1000 Mbit/s 0.512 µs 25 m

Table 2-3 Influence of the transmission rate on the collision window and maximum transmission path

* maximum transmission path for copper cable

** maximum transmission path for coaxial cable


Different approaches to improving performance

Different methods of approach are being followed to improve performances.

• Segmentation: Splitting up the collision domains• Higher band widths: Fast Ethernet, Gigabit Ethernet• Switching: Switched Ethernet

and combinations of the above.

Ethernet will not just be of interest to, but will become practical for industrial automation when these budding solutions are put into practise, in particular those for higher bandwidths and switching. For this reason, only Fast Ethernet, Gigabit Ethernet and Switched Ethernet will be described in the following sections.

Fast Ethernet

Fast Ethernet to IEEE 802.3 is not a new standard, but a further development of the ‘classic’ Shared Ethernet with the following new features:

• Data transmission rate: 100 Mbit/s• Operating mode: Full or Half duplex• Auto-negotiation• Flow Control• Trunking

These features form the basis for industry-standard Ethernet networks. Compatibility with ‘classic’ Ethernet is guaranteed by Auto-negotiation as defined in IEEE 802.3.

Ethernet Fast EthernetStandard IEEE 802.3 IEEE 802.3u

Data transmission rate 10 Mbit/s 100 Mbit/s

Bit slot time 100 ns 10 ns

Collision window 51.2 µs 5.12 µs

Access method CSMA/CD

Largest data packet 1518 bytes

Smallest data packet 64 bytes

Length of address field 48 bits

Topology Star, tree, and line topologies

Table 2-4 Comparison between Ethernet and Fast Ethernet

Auto-negotiation

Under the Auto-negotiation protocol, the two respective stations making contact exchange data packets to check their respective technical characteristics and determine an optimum operating mode.

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The parameters include:

• Data transmission rate (10 / 100 / 1000 Mbit/s)• Full / Half duplex• Support of flow control

Flow Control

Flow control provides the possibility of slowing down the flow of data by temporarily stopping it. This option is always required when a station is threatened with storage overflow. The flow control mechanism for 10 / 100 / 1000 Mbit/s is defined in IEEE 802.3z.

Trunking

Trunking is the use of several parallel, physical transmission channels between two network stations (for example, between two switches). Trunking aims on the one hand to increase transmission capacity and on the other to increase fault tolerance.

Full duplex operation

For the connection, Full duplex (FDX) means the possibility of transmitting and receiving simultaneously. Both transmission lines are physically and logically separate from one another. That not only requires special media for transmissions (for example, a copper wire respectively for each direction), but also suitable transceivers and software drivers at both ends.

Thus, theoretically, Full duplex operation doubles the bandwidth to 200 Mbit/s.

Full duplex is particularly advantageous when used between switches and stations or between several switches. Because no collisions can occur, CSMA/CD is not required.

Gigabit Ethernet

In comparison with Fast Ethernet, Gigabit Ethernet provides tenfold exploitation of the available bandwidth for Ethernet networks. Apart from the higher band-width, Gigabit Ethernet offers the advantage of compatibility with Ethernet and Fast Ethernet. Gigabit Ethernet is also based on the CSMA/CD method for data collision recognition. The same network operating systems and respective application and management software used for Ethernet / Fast Ethernet can be run without substantial alterations.


Ethernet Fast Ethernet Gigabit EthernetStandard IEEE 802.3 IEEE 802.3u IEEE 802.3z

Data transmission rate 10 Mbit/s 100 Mbit/s 1000 Mbit/s

Bit slot time 100 ns 10 ns 1 ns

Collision window 51.2 µs 5.12 µs 0.512 µs

Access method CSMA/CD

Largest data packet 1518 bytes

Smallest data packet 64 bytes 512 bytes (smaller data packets with

Carrier Extension)

Length of address field 48 bits

Topology Star, tree line topology

Table 2-5 Comparison of Gigabit Ethernet with Ethernet and Fast Ethernet

Operating modes

Gigabit Ethernet can operate in both Half duplex and Full duplex modes. Whereas Full duplex operation is largely identical with that of Ethernet / Fast Ethernet, Half duplex operation is problematical:

If the 51.2-µs collision window (please refer to section ‘Network Access Method CSMA/CD’) for Ethernet is shorted by a factor of 100 or 5.12 µs in the case of Fast Ethernet is shortened by a factor of 10, then this collision window will amount to just 0.512 µs. As this is double the maximum signal propagation time between two nodes on the common transmission medium, this collision window would allow the use of only very short lengths of cables (approx. 10 to 20 m), which would be completely unacceptable for practical use.

That is why the collision window for Gigabit Ethernet was ‘fixed’ at 4096 bits (euqivalent to 512 bytes or 4.1 µs). A trick was employed to guarantee this ‘fix’ without making changes to the data frame format: the Carrier Extension.

Carrier Extension

With a minimum of 512 bytes (19 protocol bytes and at least 493 data bytes, Gigabit Ethernet frames fulfil the 4.1-µs time condition for the collision window stated above; the 7 bytes for the preamble are ignored). Gigabit Ethernet frames with less than 493 bytes of data (46 to 492) are padded out with a Carrier Extension (see graphic below). The Ethernet frame itself remains unaltered, so that there is no difference as far as the communications software is concerned.

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Figure 2-12 Carrier Extension for a short Gigabit Ethernet frame (data field < 493 bytes)

Preamble Preamble (without starting frame delimiter)SFD Starting frame delimiterDA Destination addressSA Source addressTF Type field (length)Data Field Data field with user data (possibly including up to 46 bytes of supplementary

characters).FCS Frame check sequenceCE Carrier Extension; between 447 and 1 byte in length

Carrier Extension is implemented by the physical layer (1).

Frame Bursting

If Carrier Extension becomes necessary, the length of the Ethernet protocol overhead also increases. Gigabit Ethernet utilizes ‘frame bursting’, which is also integrated on the physical layer, to compensate as far as possible for this increase in length. Several short data blocks are packed into an Ethernet frame on the physical layer to achieve the required minimum length of 512 bytes without having to use the Carrier Extension facility.

Topology

The following characteristics are typical to a Gigabit Ethernet topology:

• Group formation• Hierarchical structures with switches• Full duplex operation

In contrast to Ethernet and Fast Ethernet, Gigabit Ethernet utilizes all 4 pairs of a twisted pair cable. This allows the data in Full duplex mode to be simultaneously transmitted and received via 2 pairs respectively, which equates to doubling the data transmission rates to 2000 Mbit/s.

10 Gigabit Ethernet

10 Gigabit Ethernet is presently the fastest variant of Ethernet transmissions with product specifications for the corresponding devices standardised in the IEEE 802.3ae. As far as industrial communications are concerned, 10 Gigabit Ethernet is only of note when networking to the higher levels is carried out via the automation level (plant control or management level) or WAN (Wide Area Network). In comparison, 10 Gigabit Ethernet is hardly used directly in industrial environments; this is because segments can be always formed in industrial facilities with their own collision domains, and lower data transmission rates are the consequence.


Ethernet with switching (Switched Ethernet)

Definition

Switched Ethernet is a network in which each Ethernet component is assigned to a port in a switch. That means that only one station is ever connected to each port. As a result, the system is divested of previous collision domains in individual point-to-point connections between network components and participating terminal devices.

Preventing collisions ensures that each point-to-point connection has exclusive use of the full network bandwidth. That means that Full duplex operation is possible. The second pair of Ethernet wires required for collision detection can now be additionally used for transmissions, which leads to a considerable increase in data throughput. That means that using Fast Ethernet (100Base-TX) it is possible to transmit 100 Mbit/s simultaneously in both directions, which, under certain circumstances, amounts to doubling the data transmission rate.

Further information on switches is contained in the following chapter in the section ‘Ethernet Switches’.

Advantages

Utilizing Switched Ethernet offers the following advantages:

• Guaranteed collision-free networks, because only one component is assigned to each port

• Rapid switching of data packets• Considerable increase in data throughput as a result of Full duplex operation• Deterministic operation is possible due to elimination of collisions.

Network size

In theory, there is no limit to the possible size of a Switched Ethernet network. The maximum cable length of a point-to-point connection is determined only by the physical transmission properties, which according to specifications is 100 m.

In practice, the actual possible length of the cable is determined by the types of connectors and lines used.

Response times

Switched Ethernet eliminates all uncertainties with regard to time arising from the collision resolution algorithm (CSMA/CD) used by Ethernet. Correctly dimensioned, Switched Ethernet can be operated as a deterministic system, meaning, its response times can be predicted. In this case, it must be guaranteed that the switches operate within their deterministic range under all operating conditions through correct selection of switches and appropriate dimensioning of the network.

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2.3 Industrial Ethernet Network

Why Ethernet for industry?

At the present time, three major trends are developing in automation:

• Intelligence is increasingly being shifted towards individual field components, forming decentralized, distributed structures of automation (distributed intelli-gence).

• The demands from within automation for IT standards are becoming difficult to overhear.

• Vertical communication is becoming increasingly integrated through all levels of the automation pyramid.

In principal, distributed intelligence can be implemented independent of the fieldbus system being operated. However, with integrated communication in mind, consideration should be given to combining with future-proof protocols when planning intelligent field devices.

Fieldbus technology as it presently stands, makes it difficult to integrate communication across all levels of the automation pyramid using a bus system. Gateways are necessary to facilitate communication between the fieldbus systems established in the lower levels (PROFIBUS, AS-Interface, CAN and others) and the bus systems in the upper levels (mostly Ethernet). As well as leading to a loss of quality, gateways can primarily be the cause of time delays and as a result hinder or even prevent integrated fast communication.

As well as the different protocols, which in part are required by or support other network structures, substantial disadvantages in present-day industrial communications include a large number of protocols and vender-specific sub-assemblies with their associated high costs for installation, maintenance, repair as well as their heterogeneous stock of data in the form of widely differing data formats.


Figure 2-13 Conventional system extension operating different fieldbus systems

Making use of Ethernet, right down to the lower levels of the automation pyramid, will (to a large extent) sweep away these weaknesses in communication. The aim is to use just one common bus protocol with uniform data formats. Using components based on Ethernet reduces the complexity of installation, maintenance and repair tasks, which in turn lowers the costs for connecting machines and systems to the fieldbus communication. And we should not forget that there is a great deal of potential for savings to be gained by using proven, standardized components, for example, RJ45 connectors as well as passive and active devices.

Neither should we forget to mention the fact that in the age of industrial Ethernet there are also various Ethernet standards and variants of protocols being used for fast communication on the lower levels that demonstrate little or no compatibility with one another. That on the one hand can be attributed in part to diverging demands (required of real-time capability for example) and on the other hand to the fact that none of these variants has (yet) managed to assert itself as the standard. The section ‘User Organisations and Protocol Variants’ contains more on this subject later in this chapter.

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Figure 2-14 System extension based on Ethernet / Industrial Ethernet

It goes without saying that the Ethernet only having been used in office environments will initially have to be adapted to suit industrial requirements, which are imperative for communication purposes in the lower levels. As well as the restriction or elimination of collision domains, these include real-time capability and Full duplex operation.

The unbeatable advantage gained from utilizing Industrial Ethernet as an integrated communication system is to be found in the use of a millionfold tried-and-trusted uniform protocol in the form of Ethernet with TCP/IP – from the office environment through to the machine / sensor. The use of this Ethernet standard means that today it is already possible to achieve economic applications for use in industry based on standard solutions. Work continues on unresolved questions and demands with regard to real-time capability, speed and reliability (as in freedom from collisions) and other characteristics necessary in industrial environments. Solutions will be found for these in the near future.

A further big advantage of Industrial Ethernet is its transmission speed: data transmission rates between 10 and 1000 Mbit/s are available with Industrial Ethernet compared to ‘just’ a few Kbit/s through to a maximum of 12 Mbit/s offered by conventional fieldbus systems.


In summary, it can be said that in comparison with conventional fieldbus systems Industrial Ethernet offers the following advantages:

• Ethernet is an open standard in use across the globe, which means, simple interaction between the devices and components from various vendors is guaranteed.

• Ethernet is open and transparent. Different protocols can be utilized simultane-ously in the same network.

• Data transmission rates from 10 Mbit/s through to 1000 Mbit/s are possible.• Conventional fieldbus systems have already been in use over a long period of

time. New installations are planned encompassing progressive and universal methods.

However, despite the euphoria surrounding Industrial Ethernet, it should not be forgotten that the ‘big’ conventional fieldbus systems (for example, PROFIBUS, CANopen, INTERBUS, ARCOS) represent more than 80 % of all the presently installed bus systems. Consequently, Industrial Ethernet will have to demonstrate over the next few years that it can supplement and replace the conventional fieldbus systems.

Fields of applications for Industrial Ethernet

Today, Industrial Ethernet can be implemented in (nearly) all fields in which fast cross-level communication between the field level and the higher levels is important, and large amounts of data have to be transferred.

The majority of Ethernet components presently in use are represented by office devices adapted to suit industrial purposes. These IP 20 devices are mostly installed in switchgear cabinets or control rooms. These devices are only of little or no suitability for use in harsh industrial climates.

However, it is possible to use devices and components sealed to protection class IP 65 / IP 67 in applications in immediate industrial environments without additional protective measures. It does not matter if these are in steelworks in extreme temperatures and dust ridden conditions, in the automotive industry controlling industrial robots or in wind turbines facing high degrees of mechanical and EMC stresses – today, Industrial Ethernet dominates a large part of industry, and it continues to advance.

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Figure 2-15 Harsh industrial conditions – operating in a steelworks

Figure 2-16 Fast data transmission to control industrial robots manufacturing automobiles


Figure 2-17 Wind turbines – high demands on EMC and mechanical stability

General requirements placed on Industrial Ethernet networks

International standard ISO/IEC 11 801 and its European equivalent EN 50 173 define a standard generic communication network for a building complex. Both standards are basically identical. Both are based on building premises used for office purposes, and both aim to set generic standards. The specific requirements placed on Ethernet networks in industrial networks such as:

• System specific cable routing• Individual degree of networking for each machine / system• Line network topologies• Robust, industry-standard cables and connectors with specific requirements

relating to EMC, temperature, humidity, dust and vibration

are not taken into consideration in either of these standards in line with what we know today. The conditions for the industrial use of Ethernet are presently being described in the revision of the EN 50 173 and its new supplements.

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The essential differences between operating Ethernet in an office environment and in an industrial environment are demonstrated in the overviews below:

Office areas Industrial areasInstallation requirements

• Permanently installed basic installation

• Cables routed in intermediate flooring

• Variable workplace device connections

• Pre-assembled device connection cables

• Generally standard work-places (desk with PC …)

• Tree network topologies

• Wiring very dependent on system requirements

• System specific cable routing• Connection points rarely altered• Devices connected on site• Individual degrees of networking

required for each machine / system

• Often linear and (redundant) ring topologies

Transmission performance

• Large volume data packets (for example, images)

• Medium network availability• Transmissions timed in

seconds• Predominantly acyclic

transfers• No isochronism

• Small data packets (for example, measurement data)

• Very high network availability• Transmissions timed in micro-

seconds• High proportion of cyclic transfers• Isochronism

Environmental requirements

• Moderate temperatures• Low levels of dust• No moisture• Low levels of vibration• Low levels of EMC exposure• Low mechanical hazard• Low levels of UV radiation• Extremely limited chemical

hazard

• Extreme temperatures• High levels of dust• Moisture possible• Vibrating machines• High levels of EMC exposure• Risk of mechanical damage• UV exposure in open-air

environments• Chemical hazard from oil-filled

and / or aggressive atmospheres

Table 2-6 Different requirements for office and industrial environments


Office areas Industrial areasSupply voltage 230 V AC 24 V DC

Mounting Desktop device, cabinet or wall mounted

Top-hat rail, wall mounted

Design size Flat Slim

Operating temperature 0 °C to +40 °C • -40 °C to +70 °C • 0 °C to +55 °C

Shock - 15 g

Vibration - 2 g

Cooling Fan Heat sink

Degree of protection IP 20 / IP 30 • IP 20 (with protective housing)

• IP 65 / IP 67

Resistance to Dust Dust, oils, solvents, acids, …

Tests, safety EN 60 950 EN 60 950

Tests, EMC • EN 50 081-1 (residential)• EN 50 082-1 (residential)

• EN 50 081-2 (industrial)• EN 50 082-2 (industrial)• DIN EN 50 155

(railway standard)

Response time > 100 ms < 20 ms

Operational lifetime > 3 years > 6 years

Availability (spare parts)

4 years 10 years

Table 2-7 Different requirements for network components in office and industrial environments

Further standardisation, such as special requirements for industrial applications will be specified in EN 50 173 supplements.

Freedom from collisions

The ability to calculate the communications is an essential requirement when running Industrial Ethernet. As Ethernet as such is not deterministic, and it is not possible to achieve clearly defined time-scheduled statuses employing the CSMA/CD method of collision recognition, other solutions will have to be found for its use in industry.

As well as the use of switches (please refer to the section ‘Ethernet With Switching’ in this chapter), various suppliers of industrial components have developed different concepts for solutions. These include, amongst others:

• Cyclic Ethernet operation whilst avoiding standard Ethernet communication (example: as with PowerLink Protection Mode or EtherCat)

• Standard Ethernet with additional real-time mechanisms (example: PROFINET or EtherNet/IP)

• A combination of both concepts (example: PROFINET)

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Real-time capability

Real-time communication capability is a further fundamental requirement for Industrial Ethernet networks. Real-time in this sense means the capability of a network to fulfil the scheduled requirements of an application under all operating conditions. With regard to transmission speeds, Ethernet as such is superior to every conventional fieldbus system. However, it is exactly the component used to guarantee compatibility with the office environment, the so-called TCP/IP stack, that is the cause of the biggest delays in the network. For that reason, the simplest solution would be to circumvent this stack; the result, however, would be the loss of compatibility to the office world.

Various solutions are being put forward to fulfil the demands for real-time capability:

• Using a so-called ‘master clock’ to synchronise the clocks of the network stations

In this case, IEEE 1588 is applied. This standard specifies a protocol for the precise synchronisation of networked systems (PTP; Precision Time Protocol), which is particularly suitable for Ethernet TCP/IP (example: JetSync).

• Cyclic communication by circumventing the TCP/IP stack For real-time communication, the TCP/IP stack is completely circumvented

and replaced by a separate stack for cyclic processes. A time slot is contained in each cycle in which ‘normal’ TCP/IP or UDP/IP protocols can be transmitted as required. Transmission is made by means of a broadcast telegram so that all stations on the network can ‘hear’ the telegrams. Ethernet switches are not allowed for this process, as these have a fundamentally longer and fluctuating transfer time. Instead hubs are prescribed (example: ETHERNET PowerLink).

• Other means of circumventing the TCP/IP stack Other methods of circumventing the TCP/IP stack address their real-time

extension directly to the MAC level (example: EtherCat) or they circumvent the TCP/IP stack by using another method (example: PROFINET).


User organisations and protocol variants

IAONA

Nowadays, the question is no longer asked if Ethernet suitable for use in industry. Owing to the technological advancements in Fast Ethernet and Gigabit Ethernet, in switching and Full duplex transmissions, the classic Ethernet has become suitable for use in industry and is becoming increasingly interesting for vendors. It would be more accurate to say that the question about the proper protocol has become more a question of what you believe.

There are presently many different approaches towards application protocols, all of which are founded in various basic principles and are not compatible with each other. In order to at least co-ordinate the activities of these individual companies and organisations, the umbrella organisation IAONA (Industrial Automation Open Network Alliance) was founded. In co-operation with the various interested parties, this umbrella organisation for industrial communication via Ethernet is dedicated to working towards minimising the differences between the individual approaches to solutions. The first result was the publication of a guideline for industrial cabling of Ethernet: the ‘Industrial Ethernet Planning and Installation Guide’, which is now available in its fourth version.

The IANOA works in close co-operation with the following partner organisations:

• EPSG (ETHERNET PowerLink Standardization Group) for ETHERNET PowerLink

• ETG (EtherCAT Technology Group) for EtherCAT• IGS (Interest Group Sercos Interface) for Sercos III• Modbus-IDA (Modbus Interface for Distributed Automation) for Modbus/TCP• ODVA (Open DeviceNet‘s Vendor Association) for EtherNet/IP

Different Approaches to Solutions

The user is spoilt for choice when it comes to selecting different protocol variants for use in industrial applications. As Ethernet has only recently been deployed in industrial automation, none of these various protocols has been able to become established as the standard. Which of the protocols the users will put their faith in will become apparent in the near future.

The following overview does not offer an evaluation and does not purport to be complete or comprehensive.

50

Ethernet protocol

Architecture Hardware Response time *

EtherNet/IP Open Standard Cycle: 500 µs - 10 ms Jitter: 500 ns

ETHERNET Powerlink

Real-Time subnet Standard Cycle: < 400 µs Jitter: < 1 µs

PROFINET Real-Time subnet Standard / dedicated**

Cycle: 5 - 20 ms (V2); 1 ms (V3) Jitter: < 1 µs with 100 synchronised drive elements

EtherCAT Real-Time subnet Standard Cycle: 100 µs with 100 synchronised drive elements

HSE Open Standard No details

JetSync Open Standard Cycle: < 5 ms Jitter: < 10 µs

Modbus-IDA Open Standard Cycle: approx. 5 - 10 ms

safeethernet Open Standard No details

SERCOS-III Open Standard / dedicated

Cycle: 1 ms; Jitter: < 1 µs with 40 axses

Table 2-8 Overview of the current Ethernet protocols

* All details in accordance with vendor specifications

** Standard-ASICS with switch supported by HARTING

Further details about the individual protocol variants are available from the corresponding websites. The Appendix contains an overview of the protocol variants and the corresponding websites.

EtherNet/IP

EtherNet/IP combines and supplements TCP/IP and UDP/IP /IP to allow industrial applications to communicate; it was presented by the ODVA (Open DeviceNet Vendor Association) at the end of 2000. The abbreviation IP in EtherNet/IP stands for Industrial Protocol.

Built on Ethernet TCP (UDP)/IP, EtherNet/IP is essentially a ported version of CIP (Control and Information Protocol) already in use in both ControlNet and DeviceNet. Secured data transmission for acyclic messages (programme upload/programme download, configuration) is implemented via TCP. Time-optimised transmission of cyclic control data is performed with UDP.

Switches can be used to improve performance.


ETHERNET Powerlink

ETHERNET PowerLink was originally developed by the Austrian company Bernecker + Rainer (B&R) with approval of the standard published in 2002.

With this protocol, TCP/IP and UDP/IP are extended by the PowerLink protocol on the layers 3 and 4. With the help of the SCNM method (Slot Communication Network Management) this PowerLink protocol completely regulates data traffic on the network to provide real-time capability on Ethernet. Each station on the network has a timed and strictly limited access, which allows it to broadcast data to every other station on the network. The possibility of collisions is fully ruled out as only one station can access the network at a particular time.

In addition to these individual time slots for cyclic data traffic, SCNM offers joint time slots for the purpose of acyclic data exchange.

Moreover, Ethernet PowerLink version 2 contains additional communications and device profiles that are closely oriented to the corresponding CANopen profiles.

Switches can only be deployed in the ETHERNET PowerLink open mode. It is not possible to use switches when in the protected mode.

PROFINET

First introduced to the market in 2002, PROFINET was developed by the PROFIBUS® User Organisation (PNO) with the support of Siemens. For the first time, the current PROFINET versions support two communications mechanisms. A standard communications channel is available for non-time critical communication (non real-time) based on TCP/IP. An optimised, software-based communication channel has been implemented for real-time communication. This channel circumvents the layers 3 and 4 to shorten the protocol data sizes and consequently the throughput times of the data packets. In accordance with IEEE 802.1p, PROFINET prioritises the data packets for optimum communication; the highest priority 7 is awarded for real-time communication. Utilizing special ASICs in which a hardware solution for the real-time channel is implemented is another method used to achieve real-time communication.

Switches are only permitted for network structuring purposes. The use of hubs is not permitted with PROFINET.

52

Further protocol variants

In addition to the named user organisations in which HARTING is a participating member, other protocol variants and standards also exist (please refer to table 2-8):

EtherCAT

The Ethernet-based automation concept EtherCat (Ethernet for Control Automation Technology) was developed by a company called Beckhoff. The ETG (EtherCAT Technology Group) is an alliance of companies whose aim it is to support and advance this technology.

In conventional Ethernet-based automation concepts, an Ethernet data packet is received by every I/O module, interpreted and forwarded. Contrast this with EtherCAT technology where the data for each I/O terminal is removed when the telegram passes through the corresponding device. Input data is inserted into the telegram as it runs through the device in the same manner. The delay to the telegrams during this process can be measured in nanoseconds.

Switches can only be used to a limited degree.

HSE

Supported by the Fieldbus Foundation, HSE (High Speed Ethernet) is mainly represented on the American market. HSE operates as a backbone and is connected to an underlying fieldbus (for example, H1) by means of gateways.

JetSync

The company Jetter developed its own protocol that can be used for synchronisation purposes based on Ethernet TCP/IP. In doing so, it uses a process that enables asynchronous data transfers to be carried out in accordance with IEEE 1588.

Modbus/TCP

Developed by Modicon (Schneider Electric), Modbus/TCP is derivative of the modbus protocol. The corresponding specification was published in 1999 and is available free of charge via the internet. The Ethernet-based protocol runs over layer 4 (TCP or UDP). It is a simply structured, open and widely available transmission protocol used for connection-based and secured exchange of data in a master-slave structure.

safeethernet

safeethernet is based on standard Ethernet and as such enables utilisation of all known IT protocols. The main field of application for safeethernet is networking safety-related applications.

SERCOS-III

Sercos interface (Serial Real-Time Communication System) is a digital interface between the controls and drives in which fibre optics is used as the transmission medium (ring). In the latest version III, the entire Sercos concept has been ported to Ethernet.

533 Transmission Technology and Cabling for Industrial Ethernet


The European Standard EN 50 173 specifies in detail the structured cabling of Ethernet networks. Although the standard focuses on office areas, substantial features can also be applied to industry.

The following two graphics depict EN 50 173-1-compliant structured cabling in the office area and the corresponding cabling for the industrial area.

Matching components in both areas are depicted in the same colour.

TO TO

TO TO

TOFDBD

FD

FD

CD

TO TO

TO TO

TOFDBD

FD

FD

Figure 3-1 Structured cabling in the office area in accordance with EN 50 173-1

CD ... Campus Distributor

BD ... Building DistributorFD ... Floor DistributorTO ... Telecommunication Outlet

54

BD

TO TO

TE TETETETE

MD

TETETE

MD

TO

Production area

ISO / IEC 11 801Structuredbuilding area

network

Structuredmachine area

network

Figure 3-2 PROFINET-compliant structured industrial network in accordance with EN 50 173-1

BD = Building Distributor

TO = Telecommunication Outlet (coupling IP 20 and IP 65 / IP 67 in the industrial area)MD = Machine DistributorTE = Terminal Equipment

In addition, various standards define cabling and networking of Ethernet stations in industrial applications. For example, the IAONA guideline ‘Industrial Ethernet Planning and Installation Guide’ offers a general overview of cabling and specifications for cables and connectors.

Individual user organisations have published their own such guidelines. For example, based on fundamental EN 50 173-1 requirements, ‘PROFINET Installation Guidelines’ define industry-standard cabling for Industrial Ethernet.

These PROFINET and other guidelines specify cables and connectors that enable the user to implement an installation for the corresponding protocol without having to specifically calculate the transmission path.

The guidelines named above set new standards because:

• The component manufacturer is provided with unambiguous specifications for interfaces.

• The user is provided with simple rules for installation.• As with fieldbus, these guidelines enable him to create networks without

additional Ethernet-specific planning.


3.1 Network topologies

Industrial Ethernet network topologies are oriented towards the requirements of the facilities to be networked. The most frequently used types of topologies are star, tree, line and ring. In practical applications, systems often consist of a mixture of these structures, which we will consider individually in the following.

Ethernet hubs, switches, routers or gateways can be utilized as central units for signal distribution purposes. Individual topologies are demonstrated in the following examples with Ethernet switches utilized as central units.

Star

Star topologies are characterised by a central signal distributor (for example, a switch) with individual connections to all terminal equipment on the network.

Star network topologies are suitable for applications with a high density of devices in a relatively short linear expansion, for example, small manufacturing cells or individual production machines.

TE

TE

TE

TE

TE

SW

Figure 3-3 Star topology with an Ethernet switch

SW = Switch

TE = Terminal Equipment

Tree

Tree topologies are created by connecting several star structures to form a network. Tree topologies are suitable for subdividing and structuring complex systems.

56

TE

TE

TE

TE

SW

TE

SW

TE TETE

TE

SW

TE TE

Figure 3-4 Tree topology with Ethernet switches

SW = Switch


Line

Line topologies can be implemented with a standalone switch close to the terminal device to be connected or by a switch integrated in the terminal device itself.

Line topologies are preferred in extensive systems incorporating longer distances, for example in conveyor systems, and for connecting manufacturing cells.

TE

SW

TE

TETETE

SW

SW SW SW

Figure 3-5 Line topology with Ethernet switches

SW = Switch


Ring (redundancy)

A ring topology is created by connecting both ends of a line topology. This additional (redundant) line is activated if a failure occurs within a line to prevent the entire network from failing.


Ring topologies are utilized in facilities with higher requirements with regard to maximum plant availability in the event of a line breakage or network component failure.

3.2 Active and passive network components

In order to build a structured Ethernet network, active and passive network com-ponents are required as well as the classic components (cable and connectors). In addition to providing the link between various levels within a structure or bet-ween different degrees of protection (IP 20 ↔ IP 67), these components are responsible for routing and distributing data telegrams.

Often equipped with an ‘intelligent’ chip, active components include those that can process, amplify and appropriately relay incoming data telegrams. For example, gateways, routers, switches and hubs (repeaters) belong to this group. These active components operate on different layers of the ISO/OSI Reference Model:

Application Layer

Presentation Layer

Session Layer

Transport Layer

Network Layer

Data Link Layer

Physical Layer

Application Layer

Presentation Layer

Session Layer

Transport Layer

Network Layer

Data Link Layer

Physical Layer

Gateway

HubRepeater( )

Switch /Bridge

Router

layers supported by Ethernet

higher layers

Figure 3-6 Ethernet components in the ISO/OSI Reference model

Fulfilling a variety of tasks, passive components are the bridge between IP 20 to IP 67 environments or serve as panel feed-throughs in switchgear cabinets. Outlets or panel feed-throughs are typical components of this group.

The following sections contain further information about gateways, repeaters, switches, bridges, hubs and outlets. In particular, we will concentrate out focus on switches, hubs and outlets, as these components represent the most frequently used device types in industrial networks.

58

3.3 Ethernet gateways

Gateways are components used on layer 7 of the ISO/OSI Reference Model to link networks utilising different protocols. For example, they are used to couple Ethernet networks with conventional fieldbus systems (such as, PROFIBUS). Due to the fact that these two networks make use of very different protocols, the data telegrams must be adapted to suit the other respective structure.

2.

1.

3.

4.

5.

6.

7. Application Layer

Presentation Layer

Session Layer

Transport Layer

Network Layer

Data Link Layer

Physical Layer

TCP / UDP

IP

CSMA/CD

Ethernet

Master - Slave

PROFIBUS

Transmission protocol

Higher-level protocol



OSI Reference model Ethernet Layers

Applicationprotocols *

Applicationprotocols

not used byPROFIBUS

PROFIBUS Layers

Figure 3-7 Comparison of Ethernet and PROFIBUS structures based on the ISO/OSI Reference Model

* ... not applicable to PROFIBUS-DP

Gateway

Conversion

Layer 1Layer 2

Layer 3

Layer 4

Layer 5

Layer 6

Layer 7

Layer 1Layer 2

Layer 3

Layer 4

Layer 5

Layer 6

Layer 7

EthernetTelegram

PROFIBUSTelegram

Figure 3-8 Function principle of a gateway (example: Ethernet and PROFIBUS)

The conversion process typically entails extensive calculations, and as such places high demands on the devices being utilized.

Belonging to the ‘intelligent’ group of devices, gateways are mostly equipped with extensive configuration and diagnostics functions. And because they operate as a station on Ethernet, each gateway is assigned its own MAC address.


Industrial Ethernet

Sensor SensorSensorSensor

PROFIBUSPROFIBUS

Gateway

Sensor

Monitoringunit

Operatingunit

Processvisualisation

PLC withgateway function

Act. Act.Act.

Remote-I/Os

Act.

Remote-I/Os

Act. = actuator

Figure 3-9 Gateways as a link between Industrial Ethernet and PROFIBUS (Example)

3.4 Ethernet router

Routers operate only in a network environment in which all stations use the same network protocol, and determine optimum routes between two stations across different transmission lines. Should the transmitter and the receiver be in different networks, the data telegram is initially addressed to a suitable router, which then determines the optimum path for the data telegram before forwarding it to another network or different router. In doing so, it makes use of previously determined tables or to be more exact applies an ‘IP routing algorithm’.

From the point of view of reliability and performance, routers are decisive components; they are frequently used in extensive structures often consisting of several networks.

Router

Router

Router

Station11

Station12

Station13 Station

21

Station22

Station23

Station24

EthernetNetwork 3

EthernetNetwork 2

EthernetNetwork 1

Direct communikationbetween stations

in the same network

Communikationbetween stationsin different networksperformed via routers

Figure 3-10 Communication between Ethernet networks with routers

60

3.5 Ethernet bridges

Ensuring communication between networks in accordance with protocols, bridges operate on layer 2 of the ISO/OSI Reference Model. Based on their MAC address, data packets are transmitted from one sub network to another.

By utilizing bridges, the user is able to extend the limits of his network with regard to numbers of stations and linear expansion. Sub-dividing networks with the help of bridges means each sub network can be extended to contain the maximum number of stations and fully exploit possible linear extension.

Moreover, bridges can be used to provide a simple means of limiting failures. Faulty data packets from the data link layer are not forwarded. An analysis of the MAC address ensures that only those data packets are transmitted to the sub network with the appropriate MAC address. Consequently, this allows bridges to filter and limit the data traffic to the connected sub networks. This filter function can make a decisive contribution towards reducing the burden in large Ethernet networks.

3.6 Ethernet switches

Switches are important components in Ethernet networks. Through the creation of different topologies (star, ring, tree or line topologies) as well as dividing the Ethernet networks into individual collision domains, they allow for greater flexibility during installation.

Switch – the key network component in Switched Ethernet

Switches are active infrastructure components operating in accordance with IEEE 801.3 on layer 2 of the ISO/OSI reference model. Some switches extend their functions to the layers 1 and 3.

Ethernet switches analyse all incoming data packets then forward them to the specific port where the corresponding component is located. Multicast and broadcast telegrams are the one exception, these being sent on to all active ports on the switch.

To support correct routing of telegrams, each switch contains an address/port assignment table, which stores the destination address assigned to a specific address on the switch. As a rule, the address/port assignment table is generated and maintained by the switch in a self-learning process. With the help of this table, incoming data packets are analysed according to their destination address, then filtered and relayed to the corresponding port. If no such entry exists in the table, the incoming data packet is initially sent to all ports. If a target address responds, it is added to table together with the corresponding port.


Ethernet Data

Ethernet Data

Ethernet Data

Ethernet Data

Ethernet Data

Ethernet Data

Ethernet Data

Ethernet Data

12344A7F2267AAB1

1342

Port

Switch Matrix

PortsPorts

Switch

Address

Incommingtelegrams

Assignment table

Outgoingtelegrams

Figure 3-11 Function principle of an Ethernet switch

A single switch can ‘learn’ several thousand addresses. This becomes necessary when more than one terminal device is connected to one or more ports. This auto-sensing capability allows several independent subnets to be connected to a single switch (cascading).

Together with the connected components, each port on a switch forms its own collision domain. Consequently, it is impossible for collisions to take place with data transmitted by other stations connected to different ports. Each port in a Switched Ethernet system is assigned just one component. This rules out collisions from the outset. Thus, this guaranteed freedom from collisions considerably increases effective data throughput; it is also an absolute pre-condition for the real-time capability of Ethernet.

Switch technology makes it is possible to build up Industrial Ethernet networks that meet the high reliability standards required of industrial area applications, and be real-time capable.

Operating modes

Auto-crossing

Auto-crossing performs an automatic crossing of the send and receive wires at twisted-pair interfaces, if required. Thus, the user is able to utilize 1:1 wired cables and crossover cables on an equal basis.

Auto-negotiation

Ethernet switches support the Auto-negotiation function in the Fast Ethernet protocol. In this case, the switch agrees a transmission mode for each port to which one or more Ethernet stations are connected with regard to:

• the data transmission rate: 100 Mbit/s or 10 Mbit/s

and

• the operating mode: Full or Half duplex

62

Auto-polarity

Auto-polarity describes the automatic correction of wiring errors in twisted-pair cables that result in a polarity reversal of the data signals.

Blocking

A switch has a certain amount of ports available, which are connected to one another via the switch matrix. A switch matrix capable of handling all connections operating at full transmission rates without delay is known as a non-blocking switch. The switch is said to be blocking, if the number of simultaneous connections operating at full transmission rates is restricted.

Half duplex mode

Half duplex actually means ‘one direction at a time’. Only one transmission direction is in operation at any one time: either receiving or transmitting.

In order to recognise collisions, the CSMA/CD mechanism must be employed for Half duplex operations.

Full duplex mode

Ethernet switches support both Half duplex and Full duplex operations.

Full duplex operations under Fast Ethernet (100 Base TX) for example, allow 100 Mbit/s to be transmitted simultaneously in both directions. That is theoretically an effective doubling of the rate of data transmissions. One line is used to transmit and the other to receive. As there is no fear of collisions, the regulations regarding the CSMA/CD access procedure are not required.

Management

A switch without management functions (unmanaged switch) switches the entire data traffic according to the address/port assignment table. The user does not have to perform any configuration or parameterisation settings. The switch can be used as a Plug and Play device. Because it is not addressed as a device, an unmanaged switch does not need to be assigned a MAC address.

Managed switches control the data traffic according to set parameters. The switch-management software implemented in the switch (firmware) forms the basis for this function.

The range of management software functions varies from switch to switch. Generally, standard functions include diagnostics and parameterisation / configu-ration options. Additional management functions can be, for example, how it reacts to communication faults.

Modern switches support SNMP Management (Simple Network Management Protocol) and web-based management. These offer the user diverse management options.

Because it is considered to be a station and is addressed via Ethernet, a managed switch must be assigned a MAC and an IP address.


Store and Forward

In the ‘Store and Forward’ mode, the switch temporarily stores the complete data packet, checks it for errors and, if it is error free, forwards it to its destination port (please refer to the graphic below).

Ethernet-Header

Ethernet- Data

Ethernet-Header

Ethernet-Header

ErrorCheck

Ethernet- DataEthernet- Data

FCS

FCSFCS

trash

Store

Adress Port12344A7F2267AA81

1342

Ethernet Frame

Figure 3-12 Operating mode ‘Store and Forward’

Cut Through

In contrast to the operating mode ‘Store and Forward’ the ‘Cut Through’ mode of operation waits only until the Ethernet switch has sufficient bytes to determine the destination address of the data packet. The data packet is forwarded as soon as the Ethernet switch is able to recognise the port to which the receiver is connected.

The operating mode ‘Modified Cut Through’ is a special variation, which waits for the arrival of exactly 64 bytes. Otherwise, this procedure corresponds to the ‘Cut Through’ operating mode. The purpose of this special form is to recognise fragments of data packets that can arise, for example, due to collisions.

64

Characteristic Store and Forward Cut Through modified Cut Through

Input storage for switch evaluation

Entire Ethernet packet (all bytes)

As many bytes as necessary for the switch evaluation

64 bytes

Switch causes minimum delay

Number of bits in the Ethernet packet times lower data transmission rate (input or output port)

Number of bits required until evaluation is complete times the data transmission rate

512 bits times data transmission rate

Jitter in the delay Proportional to the length of the Ethernet packet

constant constant (64 bytes)

Error recognition and forwarding of faulty data packets

The entire Ethernet packet is checked. The switch recognises the same mistake that the receiver would.Faulty packets are not forwarded.

No error recognition All packets (including faulty) are forwarded.

Recognition and suppression of packets with less than 64 bytes (for example, collision fragments)

Different data transmission rates in input and output ports

Yes Not possible

Table 3-1 Comparison between the operating modes ‘Store and Forward’ and ‘Cut Through’

Ethernet switches with IP 20 protection

Under certain circumstances, Ethernet switches sealed to IP 20 can also apply in industrial environments. For example, they can be used for structuring networks in control rooms, for distribution of collision domains in switchgear cabinets or for connecting machines and systems in terminal boxes. In all cases, it is important that the switches are not used directly in harsh industrial environments; a separate solution (for example a panel feed-through or coupling) should be sought for the transition from IP 20 to IP 65 / IP 67 areas.

There are presently numerous suppliers offering Ethernet switches with protection class IP 20; the number of available ports varies between 4, 8 and 16. Ethernet switches for integrating into 19” racks can be equipped with even more ports.

In conclusion, it is possible to say that under certain circumstances Ethernet switches, sealed to IP 20, can offer a cost-efficient solution for use in industry. In saying that, a great deal depends on the respective tasks and the ambient conditions in which the solutions are implemented.


EthernetSwitch

IP 20

IP 67

Switching cabinetProcessContollevel

PLC

Ethernetbuildingcabling Patch

cable

Ethernet cableto the individualterminal devices

TransitionIP 20 to IP 67

Figure 3-13 Industrial utilisation of Ethernet switches sealed to IP 20

Ethernet switches with IP 65 / IP 67 protection for direct mounting

Ethernet switches with metal or plastic housings sealed to IP 65 / IP 67 are suitable for mounting directly onto the machine or system. They can either be mounted directly onto the machine using special wall mounts or onto standard mounting rails in the immediate vicinity of the machine using top-hat adapters.

The connection options for the Ethernet cable can vary between the various RJ45 variants and M12 D-coding circular connectors. In this case, the various Ethernet user organisations and vendors give priority to different solutions. Please refer to the section ‘Connectors’ in this chapter for more detailed information on individual connector variants.

66

IP 20

IP 67

EthernetSwitch

Switching cabinetProcessControllevel

PLC

Ethernetbuildingcabling

Ethernet cable to theindividual terminaldevices

Figure 3-14 Industrial utilisation of Ethernet switches sealed to IP 65 / IP 67

The table below offers a comparison of the advantages and disadvantages of using Ethernet switches sealed to IP 20 and those sealed to IP 65 / IP 67:


Ethernet switch with IP 20 protection

Ethernet switch with IP 65 / IP 67 protection

Advantages • Competition is vigorous, ensuring a large selection

• High number of ports per switch possible

• Good mounting options in switchgear cabinet (top-hat rails)

• Utilisation of power sources in vicinity possible (for example, in the switchgear cabinet)

• Use of standard cables and RJ45 connectors

• Short bridging lengths possible between controls and switch

• Direct mounting onto the machine / plant possible

• Saves space in switchgear cabinet / terminal box

• No additional protective measures necessary in harsh industrial environments

• Robust, vibration and impact proof housing – often made of metal

• Support various Ethernet specifications through different mating faces

• Short transmission paths between switch and terminal equipment possible

• Utilise standard connectors• Direct indication of diagnostic

signals by means of LEDs possible

• Just one long transmission path between the switch and PLC

Disadvantages • No option for direct mounting onto the machine / plant

• In part, large space require-ments in the switchgear cabinet

• In part, long transmission paths between the switch and terminal equipment outside of the switchgear cabinet

• Additional protective measures necessary when used outside of switchgear cabinet (for example housing)

• When mounted in switchgear cabinet or terminal box, the housing must be opened for diagnosis

• Relatively large dimensions and weight

• Maximum number of ports is limited

• Power supply with 24 V DC can prove to be difficult

Table 3-2 Comparison between Ethernet switch sealed to IP 20 and Ethernet switch sealed to IP 65 / IP 67

68

Technical features

Ethernet switches with IP 65 / IP 67 protection for direct mounting offer the following distinctive features:

• Enable terminal devices to be connected via shielded or unshielded twisted-pair cables in accordance with IEEE 802.3.

• Any network configuration (line, star, tree) is possible with the Ethernet switch.

• Safe and fast installation is guaranteed when pluggable connectors are used for all connections.

• All Ethernet interfaces are protected against overvoltage.• Ethernet switches are generally designed to be non-blocking. That means that

your switch matrix can process all connections between the ports without delay when operating full data transmission rates.

• There are various mounting sets available for direct mounting (wall mounting, mounting onto top-hat mounting rails).

• In accordance with Ethernet specifications, the ports are designed for connec-tors with protection to IP 65 / IP 67.

• The address/port assignment table is generated automatically by the Ethernet switch in a ‘self-learning process’ and stored in the volatile memory (RAM) of the Ethernet switch. Voltage resumption initiates an internal reset procedure to delete the table.

In addition, the use of Ethernet switches offers the following advantages:

• Reduced cabling work and costs when constructing industrial networks• Robust metal housings made of die cast metal or plastic materials• EMC, temperature range and mechanical stability fulfil the most stringent

requirements• Compatible with the various Ethernet specifications (for example, PROFINET

or ETHERNET/IP)


Example for an IP-65 Ethernet switch for direct mounting

The following graphic depicts a typical construction example of an Ethernet switch from HARTING:

Protection cover Han® 3 A (for RJ45 only)

Data ports DP 1...5 (example: RJ45)

Status indication Operating voltage

Status indication Operating status Data ports 1...5

Connector set for data ports (example: RJ45)

Connector for power supply (example: Han® 4 A)

Zinc die-cast housing Degree of protection: IP 65

Device identification label

Power supply feed-in (example: Han® 4 A)

Locking lever (for RJ45 only)

Type

nsch

ild

Link Act

Port 5

PowerPort 1Port 2Port 3Port 4

Ethernet SwitchESC 67

Figure 3-15 Construction of the ESC TP05U HARTING RJ Industrial®

70

Block diagram

10Base-T100Base-TxTransceiver

U1+ U1- U2+ U2-

R1

T1

24 V DC

3,5 V DC


R2

T2


R3

T3


R4

T4


R5

T5

Auto Negotiation

Assignmenttable

Figure 3-16 Block diagram of Ethernet switch ESC 67-10 TP05U

‘In-between’ Ethernet switches for mounting onto external enclosure panels

So-called ‘In-between’ Ethernet switches represent a further Ethernet switch variant for use in industry. These are Ethernet switches that can be mounted directly onto the external panel of switchgear cabinets, terminal boxes or other housings; they serve as a coupling between the IP 20 environment within the housing on the one hand, and the harsh IP 67 industrial environment on the other.

These ‘In-between’ Ethernet switches fulfil several functions at the same time:

• Ethernet ports with IP 65 / IP 67 protection levels offer the possibility of struc-turing the Ethernet network and coupling terminal equipment in external industrial areas.

• At the same time, with ports sealed to IP 20 on the rear side of the Ethernet switch they offer the possibility of structuring an Ethernet network on the inside of the housing (switchgear cabinet) as well as coupling terminal equipment in the IP 20 environment.

• Last but not least, they act as panel feed throughs linking the worlds of IP 20 and IP 67.

• To fulfil the various Ethernet specifications, ‘In-between’ Ethernet switches are also available with different connectors.

The following graphic demonstrates uses for ‘In-between’ Ethernet switches:


In-betweenEthernetSwitch

IP 20

IP 67

ProcessControllevel

Ethernetbuildingcabling

Ethernet cable to theindividual terminationdevices

Switching cabinet IP 20

Patchcable

Figure 3-17 Options for utilising ‘In-between’ Ethernet switches

Technical features

Essentially, the same characteristics apply for direct mounting as those for Ethernet switches:

• ‘In-between’ Ethernet switches enable terminal devices to be connected using shielded or unshielded twisted-pair cables in accordance with IEEE 802.3.

• ‘In-between’ Ethernet switches support all network topologies (line, star, tree) in IP 20 as well as IP 65 / IP 67 areas.

• Various ports are available to structure networks to IP 65 / IP 67 (outside switchgear cabinet)

• Ethernet stations in IP 20 areas can be connected using standard RJ45 connectors (switchgear cabinet interior).

• Pluggable connectors guarantee quick and reliable installation of all connec-tions.

• All Ethernet interfaces are protected against overvoltage.• ‘In-between’ Ethernet switches are designed to be non-blocking.

72

• The address/port assignment table is generated automatically by the Ethernet switch in a ‘self-learning process’ and stored in the volatile memory (RAM) of the Ethernet switch. Voltage resumption initiates an internal reset procedure to delete the table.

• Diagnostic message indication via LEDs on the front plate of the ‘In-between’ Ethernet switches possible.

Utilisation of ‘In-between’ Ethernet switches offers the following additional advantages:

• Reduced cabling work and costs when constructing industrial networks• Suitable as panel feed-through from switchgear cabinets or terminal boxes• Robust housings with higher shock and vibration resistance as well as EMC

compatibility• Compatible with the various Ethernet specifications (for example, PROFINET

or ETHERNET/IP)• Mount directly onto exterior panels of switchgear cabinets, terminal boxes …

Practical experience shows that network structures often consist of both types of IP 65 / IP 67 switches: sealed to IP 20, Ethernet stations are connected in a structured manner to the ports of the ‘In-between’ Ethernet switches. The structure is then routed outside of the switchgear cabinets via ports offering IP 65 / IP 67 protection levels. Additional structures can be created with the help of Ethernet switches suitable for direct mounting.

TE TE

TE

TE

TETE TE

TE

TE

. . .

Switch cabinetMachine module 1

Switch cabinetMachine module n

Figure 3-18 Example of a structure based on ‘In-between’ Ethernet switch and Ethernet switch for direct mounting

TE ... Terminal Equipment


Example for an ‘In-between’ Ethernet switch

The following graphic depicts a typical construction example of an ‘In-between’ Ethernet switch from HARTING:


Status indicators

Data ports IP 67 (example: RJ45)

Fixing strap

on the back side:

Data ports IP 20 (RJ45)

Termination for power supply

Figure 3-19 Construction of the ESC 67-30 TP05U HARTING RJ Industrial®

Block diagram


U1+ U1- U2+ U2-

R1

T1

24 V DC

3,5 V DC


R2

T2


R3

T3


R4

T4


R5

T5

Auto Negotiation

Assignmenttable

Figure 3-20 Block diagram of ‘In-between’ Ethernet switch ESC 67-30 TP05U

74

3.7 Ethernet hubs

Hub as an active network component

Operating on layer 1 of the ISO/OSI Reference Model, hubs are often referred to as ‘repeaters’. They can also partly extend their function to layer 2.

An Ethernet hub is used to implement cabling in an Ethernet / Fast Ethernet network between more than two Ethernet stations using shielded (STP) or unshielded twisted-pair (UTP) cables in accordance with IEEE 802.3. Ethernet hubs operate at speeds of 10 Mbit/s, Fast Ethernet-Hubs at 100 Mbit/s. Hubs capable of operating at both speeds are known as dual speed hubs. Cabling implemented with Ethernet hubs is less susceptible to faults and when utilised in a star arrangement has the advantage that the failure of a network node does not mean the failure of the entire network.

As well as serving to structure the network, Ethernet hubs also regenerate incoming signals and perform other tasks.

In contrast to Ethernet switches, which only forward the incoming data packets to the port to which the station with the corresponding address is connected, hubs relay all incoming data packets to all ports and their stations.

Contrary to Ethernet switches, Ethernet hubs cannot create their own collision domains to prevent collisions. Thus, Full duplex operations are not possible. Ethernet hubs operate only in Half duplex mode.

Hub Switch

TE

TE TE

TE

TE

TE TE

TE

Ethernet hub Ethernet switch

Figure 3-21 Difference between an Ethernet hub and an Ethernet switch

TE = Terminal Equipment (Datenendgerät)


Hub

Ethernet Data

Ethernet Data

Ethernet Data

Ethernet Data

Ethernet Data

Ports

5

4

3

2

1

Ports

5

4

3

2

1

Ethernet Data

Ethernet Data

Incommingtelegrams

Outgoingtelegrams

Figure 3-22 Function principle of an Ethernet hub

Operating modes

Auto-sensing

Auto-sensing makes it possible for Ethernet hubs to automatically recognise the data transmission rate (10 Mbit/s or 100 Mbit/s) and to transmit and receive data at the same rate. If terminal devices operating with different transmission rates are connected to a hub, the hub will automatically function with the higher trans-mission rate of 100 Mbit/s. That guarantees that existing Ethernet connections operating with 100 Mbit/s are not stalled by a factor of 10 should a terminal device operating with 10 Mbit/s be connected.

In this case, communication with terminal device(s) or equipment operating with 10 Mbit/s is not performed via the Ethernet hub.

These settings also apply when two or more Ethernet hubs are connected in a network (cascade).

Half duplex mode

Ethernet hubs support Half duplex operations. A single data line is used to transmit and receive signals. The other data line is used to recognise possible collisions.

Ethernet hubs with IP 20 protection

Under certain circumstances, Ethernet hubs sealed to IP 20 can be also be used in industrial environments. This allows them to be used to structure net-works in control rooms as well as in switchgear cabinets and terminal boxes. In all cases, it is important that the hubs are not used directly in harsh industrial environments; a separate solution (for example, a panel feed-through or coupling) should be sought for the transition from IP 20 to IP 65 / IP 67 areas. There are presently numerous suppliers offering Ethernet hubs with protection class IP 20, which means that the user is able to acquire the hub that exactly fits his requirements. The number of available ports varies a great deal; however, most Ethernet hubs are equipped with 4, 8, 16, 24 or 32 ports. Ethernet hubs for integrating into 19” racks can be equipped with even more ports.

76

In conclusion, it is possible to say that under certain circumstances Ethernet hubs, sealed to IP 20, can provide a cost-efficient solution for use in industry. In saying that, a great deal depends on the respective tasks and the ambient conditions in which the solutions are implemented.

EthernetHub

IP 20

IP 67

TransisionIP 20 and IP 67


PLC

Ethernetbuildingcabling Patch

cable

Ethernet cable to theindividual terminal

Figure 3-23 Industrial utilisation of Ethernet hubs sealed to IP 20

Ethernet hubs with IP 65 / IP 67 protection

Ethernet hubs with IP 65 / IP 67 protection level can, for example, be mounted directly onto the machine / system. They can either be mounted directly onto the machine using special wall mounts or onto standard mounting rails in the immediate vicinity of the machine using special top-hat adapters.


The connection options for the Ethernet cable can vary between the various RJ45 variants and M12 D-coding circular connectors. In this case, the various Ethernet user organisations and vendors give priority to different solutions. Please refer to the section ‘Connectors’ in this chapter for more detailed information on individual connector variants.

IP 20

IP 67

EthernetHub


PLC

Ethernetbuildinglevel

Ethernet cable to theindividual terminaldevices

Figure 3-24 Industrial utilisation of Ethernet hubs sealed to IP 65 / IP 67

The table below offers a comparison of the advantages and disadvantages of using Ethernet hubs sealed to IP 20 and those sealed to IP 65 / IP 67:

78

Ethernet hub with IP 20 protection

Ethernet hub with IP 65 / IP 67 protection

Advantages • Competition is vigorous, ensuring a large selection

• High number of ports per hub possible

• Good mounting options in switchgear cabinet (top-hat rails)

• Utilisation of power sources in vicinity possible (for example, in the switchgear cabinet)

• Use of standard cables and RJ45 connectors

• Short bridging lengths possible between controls and hub

• Direct mounting onto the machine / plant possible

• Saves space in switchgear cabinet / terminal box

• No additional protective measures necessary in harsh industrial environments

• Robust, vibration and impact proof housing – often made of metal

• Support various Ethernet specifications through different mating faces

• Short transmission paths between hub and terminal equipment possible

• Utilise standard connectors• Direct indication of diagnostic

signals by means of LEDs possible

• Just one long transmission path between the hub and PLC

Disadvantages • No option for direct mounting onto the machine / plant

• In part, large space requirements in the switchgear cabinet

• In part, long transmission paths between the hub and terminal equipment

• Additional protective measures necessary when used outside of switchgear cabinet (for example housing)

• When mounted in switchgear cabinet or terminal box, the housing must be opened for diagnosis

• Relatively large dimensions and weight

• Maximum number of ports is limited

• Power supply with 24 V DC can prove difficult

Table 3-3 Comparison between Ethernet hub sealed to IP 20 and Ethernet switch sealed to IP 65 / IP 67

Technical features

Ethernet hubs are distinguished by the following features:

• They enable terminal stations to be connected via shielded or unshielded twisted-pair cables in accordance with IEEE 802.3.

• Utilising Ethernet hubs reduces cabling work and costs when creating industrial networks.

• Ethernet hubs support all network configurations.


• Pluggable connectors guarantee quick and reliable installation of all connections.

• All Ethernet interfaces are protected against overvoltage.• In accordance with Ethernet specifications, the ports are designed for

connectors with protection to IP 65 / IP 67.

In addition, the use of Ethernet hubs offers the following advantages:

• Robust housings made from either metal or plastic offering higher shock and vibration resistance as well as EMC compatibility

• Suitable for harsh industrial environments• Compatible with specifications of different Ethernet user organisations (for

example, with M12 D-coding in accordance with ETHERNET Powerlink)

Cabling

When cabling, a distinct characteristic of Ethernet hubs must be considered:

Due to the fact that hubs feature an integrated cross-over function, 1:1 Ethernet cables are normally used between the hub and the connected terminal equipment.

However, when connecting two Ethernet hubs with one another (cascading), it must be ensured that the cross-over functions in both Ethernet hubs do not contrive to mutually neutralise each other. Utilising a cross-over cable, for example, when connecting the two hubs could bring this about. Various solutions are possible; one is that the cross-over function can be changed over at the respective hub port.

For this reason, it is important to observe the operating instructions of the respective manufacturer when connecting Ethernet hubs with one another.

Example for an Ethernet hub (IP 65 / IP 67)

The following graphic depicts a typical construction example of an Ethernet hub from HARTING:

80

Data ports DP 1...5 (example: M12-L D-coding)

Connector for Data ports (example: M12-L D-coding)

Connector for power supply (example:M12-L A-coding)

Power supply input (example: M12 A-coding)


Zinc die-cast housing Degree of protection: IP 65Status indication

Operating voltage

Status indication Operating status Data ports 1...5

Type

nsch

ild

Link Act

Port 5

PowerPort 1Port 2Port 3Port 4

Ethernet HubESC 67

Figure 3-25 Construction of EHB 67-10 TP05 M12 D-coding

Block diagram


R1

T1


R2

T2


R3

T3


R4

T4


R5

T5U1+ U1- U2+ U2-

24 V DC

3,3 V DC

10Base-TRepeater

100Base-XRepeater

Por

tSw

itchi

ngLo

gic

Auto-sensing

Figure 3-26 Block diagram of Ethernet hub EHB 67-10 TP05


3.8 Industrial Outlets for Industrial Ethernet

Industrial Outlet as a passive network component

Industrial Outlets are passive network components not equipped with intelligence and lacking their own power supply. In principle, they are the ‘socket outlets’ for Industrial Ethernet within the system; they are essentially tasked with continuing the structured building cabling through to the machine or system in an industrial environment in accordance with ISO/IEC 11 801:2002 and EN 50 173:2002. This allows Ethernet cables to be permanently installed in factory buildings. As pluggable modules / units, the machine and other components are connected via the Industrial Outlet as required. IP 65 / IP 67 protection levels are maintained.

If it becomes necessary to separate the machine from the Ethernet network (for example, for maintenance or replacement purposes), then all that is required is to simply disconnect the connector from the Industrial Outlet. Extending the facility is just as easy; simply ‘plug’ the new component to an existing or additional Industrial Outlet.

Figure 3-27 Structured cabling to ISO/IEC 11 801:2002 with Industrial Outlets

Industrial Plant

Machine Network

82

Essentially, an Industrial Outlet consists of the housing, a PCB with a terminal strip or other wiring option to wire the Ethernet cable to the IP 65 / IP 67 ports.

Designed with pluggable connections, Industrial Outlets are usually equipped with two or more ports with high protection levels for routing the Ethernet connection to the industrial system.

Industrial Outlets for wall mounting in industrial environments

Industrial Outlets are generally mounted directly onto walls, girders, pillars or similar. As a rule, permanent cabling is implemented using Ethernet cables routed through cable ducts or via cable bridges to the point of assembly and wired to the Industrial Outlet. The actual connection to the machine / system is implemented via a (disconnectable) plug-in connection, which can take the form of either RJ45 or M12 D-coding variants. Thus, Industrial Outlets can also be deployed in accordance with the respective Ethernet specification.

Technical features

Industrial Outlets are distinguished by the following characteristics:

• Utilising Industrial Outlets allows the structured building cabling to be fed directly through to the machine in the industrial area in accordance with ISO/IEC 11 801:2002.

• Industrial Outlets enable terminal stations to be connected via shielded or unshielded twisted-pair cables in accordance with IEEE 802.3.

• With pluggable Ethernet ports with IP 65 / IP 67 protection levels they offer the possibility of structuring the Ethernet network and coupling terminal equipment in external industrial areas.

• Utilising plug-in connectors guarantees that the Ethernet connection is rapidly and reliably connected to the terminal equipment.

• At the same time, for example, by taking advantage of LSA connection tech-nology Ethernet cables can be connected to a PCB, and as a consequence offer a rapid, simple and reliable connection between the facility network and the respective terminal device.

• Industrial Outlets are available with different connectors to comply with various Ethernet specifications. Thus, the user can select the requisite Industrial Outlet for his particular application to fulfil the respective Ethernet specifications.

In addition, the use of Industrial Outlets offers the following advantages:

• Robust housings made from either metal or plastic for a high degree of shock and vibration resistance as well as EMC compatibility

• Compatibility with the various Ethernet specifications (for example, PROFINET or ETHERNET Powerlink)

The following graphic depicts an Industrial Outlet in typical use in an industrial application:


Figure 3-28 Industrial Outlet in a production facility at Daimler Chrysler AG, Rastatt (source: HARTING)

Example for an Industrial Outlet

The following graphic depicts a typical construction example of an Industrial Outlet from HARTING:

Data ports IP 67Protection cover Han® 3 A

Labelling field Cable entries

Blanking plugs M20 to block off non-utilised cable entries

Figure 3-29 Construction of INO 67 HARTING RJ Industrial®

3.9 Cabling

For use in industrial applications, it is necessary for more than the individual components to be protected. The cables and connectors for Ethernet also have to resist what can be unfavourable effects of use in direct industrial environments. These unfavourable effects include:

• Acids, alkalines and other aggressive substances in the air and immediate vicinity.

• High humidity

84

• Mechanical stresses• Vibration• High temperature fluctuations• Electromagnetic disturbance fields

and others

In addition, the ease with which a cable can be integrated into the machine and system (for example, via cable ducting or trailing cable) and ease of handling play a large part in the decision for or against a specific cable.

Standardisation

The actual status of standardisation pertaining to Ethernet cabling in industrial areas is conspicuous by the existence of numerous standards, supplements of these and various guidelines. For example, the actual requirements for Gigabit Ethernet, which are specified in IEEE 802.3ab, have been taken on by the ISO/IEC 11 801:2002 and in the EN 50 173-1:2002.

The various user organisations prefer different product profiles for the cabling. All of these profiles will remain valid along side each other so long as there is no uniform standardisation in this field. The following table offers an overview of the product profiles issued by IANOA, ODVA and PNO (PROFINET):

Characteristic IAONA ODVA PNOWire cross-section

• Fixed cabling: AWG 22 / AWG 24

• Flexible cabling: AWG 24 / AWG 26

AWG 24 AWG 22

Shielding Yes, obligatory Yes, unshielded permissible

Yes, obligatory

Connector for IP 65 / IP 67 areas

• RJ45 compatible• M12 D-coding,

4-poles

Variant 01 of IEC 61 076-3-106

• Variant 04 of IEC 61 076-3-106

• M12 D-coding, 4-poles

Optional power supply (incorporated)

Via data line: PoE to IEEE 802.3af

Via hybrid cable and IEC 61 076-3-106 variant 05 connector

Table 3-4 Various solutions available for Ethernet cabling

The first step towards a uniform world-wide valid standard has already been taken. For example, agreements have been made that highlight the differences between the cabling in office and industrial environments. These include, amongst others:

Structure

• Line and ring structures are widespread in industrial environments, with star and tree structures more prevalent in office environments.

• Transmission media in industrial environments are:


• Copper cable, Category 5, UTP (Unshielded Twisted Pair) or STP (Shielded Twisted Pair)

• Fibre optics cable with HCS® or POF fibres (HCS® - Hard Clad Silica; POF – Polymer Optical Fibre)

• Structures complying with ISO/IEC 11 801 are being revised:• ‘Campus Backbone’ and ‘Building Backbone’ are being retained• The ‘Horizontal Cabling Subsystem’ will be divided into a ‘Floor Backbone

Subsystem’ and an ‘Apparatus Cabling Subsystem’.• The ‘Consolidation Point’ will be superseded by an ‘Intermediate/Industrial

Distributor’.• User-independent cabling ends at the interface to the application (machine or

plant component)

Environmental conditions

Essentially, two areas will be differentiated in industrial environments:

• IP 20 within control rooms, switchgear cabinet and other protected environments

• IP 65 / IP 67 in unprotected external areas

It should be noted that different industrial areas could be subjected to vastly different environmental conditions:

Industry

Vibr

atio

n

Tem

pera

ture

Moi

stur

e

Rad

iatio

n

EM fi

elds

Agg

ress

ive

fluid

s

Oils

Gas

es

Motor vehicle manufacture X - - - X X X -

Chemical X X X - X X X X

Electronics X - - - X X - -

Power stations X X X X X X X X

Mechanical engineering X - - - X X X X

Steel X X X - X X X X

Table 3-5 Environmental influences in various fields of industry

Frequently used Ethernet transmission media

Essentially, two transmission media are utilised in Industrial Ethernet:

• Twisted-pair: copper cables with 2x 2 or 4x 2 cores, twisted around each other in a spiral pattern. These cables can be shielded (Shielded Twisted Pair – STP) or unshielded (Unshielded Twisted Pair – UTP).

86

• Fibre optic cables as multimode or single mode fibre; suitable for short- or long-wave lasers

The answer to the question about the ‘right type’ of cable often depends on a number of factors. One important factor is the required transmission length between two components. Further factors can be found in electromagnetic interference, mechanical stress, the required category and other conditions.

The variants listed in the table below represent only a small selection of possible cables:

Standard Transmission medium Distance10 Mbit/s system10Base-T [FD] 2 wire pairs, mind. Category 3, UTP / STP > 100 m

10Base-FL [FD] 2x multimode fibre-optic cables > 1000 m depends on type of fibre

100 Mbit/s system (Fast Ethernet)100Base-TX [FD] 2 wire pairs, Category 5, UTP and STP 100 m

100Base-FX [FD] 2x multimode fibre-optic cables depends on type of fibre

1000 Mbit/s system (Gigabit Ethernet)1000Base-T [FD] 4 wire pairs, Category 6, UTP 100 m

1000Base-SX [FD] 2x multimode or single mode fibre-optic cables (short-wave laser)

275 m

1000Base-LX [FD] • 2x multimode fibre-optic cables (long-wave laser) or

• 2x single mode fibre-optic cables (long-wave laser)

depends on type of fibre

Table 3-6 Transmission media for Ethernet protocols

[FD] = Full Duplex operation possible

STP = Shielded Twisted PairUTP = Unshielded Twisted Pair

Characterising cables and channels

In the main, Ethernet installations are characterised by two parameters: the category of the cable, and the class of the channel.

Cable is categorised in accordance with its electrical transmission and high-frequency properties:


Specification Max. frequency Impedance ApplicationCategory 1 not specified 100 Ω Analogue speech transmissions

Category 2 up to 1 MHz 100 Ω IBM cabling, type 3 (language)

Category 3 up to 16 MHz 100 Ω 10Base-T; 100Base-T4; ISDN

Category 4 up to 20 MHz 100 Ω 16 Mbit Token Ring

Category 5 up to 100 MHz 100 Ω 100Base-T

Category 6 up to 250 MHz - 1000Base-T

Category 7 up to 600 MHz - 10Base-T

Table 3-7 Overview of cable category assignment

The channel is the point-to-point part of the transmission process; the electrical transmission and high-frequency properties are classed follows:

Class A up to 100 KHz

Class B up to 1 MHz

Class C up to 16 MHz

Class D up to 100 MHz

Class E up to 250 MHz

Class F up to 600 MHz

Table 3-8 Overview of cable class assignment for transmission channels

The requirements placed on the transmission channel and therefore on the cable become increasingly discriminating the higher letter in the alphabet. For example, if just category 5 cable is used in a system, then its performance must correspond to channel D. The same applies to category 6 and class E as well as to category 7 and class F.

600200100

Attenuation10 dB

20 dB

30 dB

40 dB

50 dB

60 dB

Next

CAT 5

CAT 7

Frequency [MHz]

Figure 3-30 Cable properties in conjunction with the category used

Next = Near end crosstalk

88

Specifications for transmission cables made of copper for Industrial Ethernet

Industry-standard cables can be subjected to extreme mechanical stress. Accordingly, the cables require a special construction, which in turn affects the transmission properties. Therefore, when using special cables, it may only be possible under certain circumstances to implement short transmission lengths.

One important question when choosing the ‘right’ cable concerns the type of installation: will the cable be installed permanently and stationary in cable ducting or similar? Or does it need to be drag-chain suitable? Depending on the location, the cable and its construction must fulfil various requirements.

The possible cable types for Industrial Ethernet are contained in the relevant IEEE 802 standards. For example, both copper or fibre optic cables can be utilised in Fast Ethernet.

Figure 3-31 Twisted-pair cable with two cable pairs (example: for permanent installation)

The following general conditions apply for standard copper cables:

• Signals are transmitted via symmetric copper cables (twisted-pairs) in accordance with 100Base-TX at a transmission rate of 100 Mbit/s (Fast Ethernet).

• The transmission medium consists of either 2- or 4-pair sets of twisted and shielded copper cables (twisted-pair or star-quad) with a characteristic impedance of 100 Ohm.

• Only shielded cables and connection elements are permitted. • Individual components must fulfil Category 5 requirements in accordance with

EN 50 173-1: 2003. • The entire transmission path must fulfil Class D requirements in accordance

with EN 50 173-1. • Non-permanent connections are created using RJ45 and M12 plug-in connec-

tion systems. • Device connections to IP 67 are designed as female connectors. • Connecting cables (device connections, patch cables) are fitted at both ends

with male connectors. • All devices are connected via an active network component.

In order to guarantee the easiest possible installation, the transmission cables are equipped with the same connectors at both ends (patch cable). The maximum transmission length is 100 m.


max. 100 m

Figure 3-32 Maximum transmission length of Ethernet cables

Using the specified cables in conjunction with the specified connectors results in a maximum cabling length of 100 m for up to 6 mated connector pairs.

Cabling examples Number of connectors

Maximum cabling length

2 100 m

2 100 m

2 100 m

4 100 m

4 100 m

6 100 m

6 100 m

Table 3-9 Maximum cabling lengths for Ethernet / Fast Ethernet according to PROFINET specifications

TE = Terminal Equipment PMD = PROFINET Machine Distributor

„Inside“ environment

Connector Coupling

90

When calculating the maximum transmission length, it is not of any significance if the cable is only to be used ‘inside’ a switchgear cabinet or outdoors, or as a connection between two switchgear cabinets.

For calculation purposes, the combination of male and female connectors is considered a pair; in this case, it does not matter if the pair is used purely for coupling purposes or if one component (connector or socket) is integrated in a device.

Each additional mated connector pair reduces the length of the transmission path. A separate calculation must be made when utilising more than 6 pairs. This calculation is described in the standard IEC 11 801, which also contains further information including additional verification of the transmission path, for example.

Hybrid cable

Hybrid cables (data line and power supply combined in one cable) are used where decentralised field devices are connected with both data and power supply via a combined connector. As well as 4 copper wires for the power supply, this cable consists of 2 or 4 sets of shielded data lines for communi-cation.

Figure 3-33 Hybrid cable with 2 sets of shielded data lines and 4 copper wires for the power supply

Special cable for Gigabit Ethernet

In comparison with Ethernet / Fast Ethernet, the most important difference when using Gigabit Ethernet is to be found in the adaptation of the components physically involved with transmissions, or, in other words, the cables and connectors. Although these components have to be designed for a higher band-width, they are ‘downward compatible’ for Ethernet / Fast Ethernet. For this reason, cables suitable for the higher performance of Gigabit Ethernet are often laid in new installations.

Cable for Gigabit Ethernet must fulfil Category 6 / Class E requirements in accordance with the cabling standard ISO/IEC 11 801:2002.

Fibre optics

Single-mode or multimode fibre optics are utilised in the Gigabit Ethernet variants 1000Base-SX and 1000Base-LX. Longer transmission paths can be achieved with single-mode fibre optics than with the equivalent multimode fibre optics. As a rule, dispersion is less with single-mode fibre optics.


Type Frequency Cable type Diameter of fibre

Transmission length (maximum)

1000Base-SX 850 nm Multimode 50 µm 550 m

62.5 µm 275 m

1000Base-LX 1330 nm Multimode 50 µm 550 m

62.5 µm 500 m

Single mode 9 µm 3000 m

Table 3-10 Special fibre-optic cables for Gigabit Ethernet

Copper cable

The copper cables used for Gigabit Ethernet are generally individually shielded twisted-pairs with a stranded core diameter of AWG 22 to AWG 26.

Pair-wise stranding with additional individual shielding is designed to guarantee an improved and cleaner differential signal transmission in comparison with normal twisted-pair cables without individual shielding. In addition, this enables common mode interferences to be eliminated.

The twisted-pair cables to be utilised can be differentiated as follows:

Twisted-pair cable Individually shielded

Overall shield

Shielded, Foiled / Unshielded Twisted Pair SF/UTP Yes No

Shielded / Pair Foiled Twisted Pair S/FTP Yes Yes

Table 3-11 Twisted-pair cables for Gigabit Ethernet

Special cable for 10 Gigabit Ethernet

Presently, only single-mode or multimode fibre optics are utilised in 10 Gigabit Ethernet.

Type Frequency Cable type Transmission length (maximum)

10GBase-LX4 1300 nm Multimode 300 m

10GBase-SR/SW 850 nm Multimode 66 m

10GBase-LR/LW 1310 nm Single mode 10 km

10GBase-ER/EW 1550 nm Single mode 40 km

Table 3-12 Overview of fibre-optic cable for 10 Gigabit Ethernet

Power on Ethernet (PoE)

The latest developments in the cabling field have the aim of guaranteeing the power supply to the connected device via the Ethernet cable. In contrast to hybrid cables, which feed the power via a separate wire, PoE (Power on Ethernet) utilises the standard Ethernet cable. The supply of energy via the standard Ethernet cable is defined in the supplement IEEE 802.3af.

92

This also includes a definition of an optional data-free supply of power, which allows power to be drawn from the data cabling system. In this case, the energy is routed via the RJ45 interface to the corresponding terminal device together with 10Base-T, 100Base-TX or 1000Base-T.

PoE itself is divided into 5 performance classes:

Class Use Classification current

Max. power supply

Max. power drawn

0 Default 0 - 15 mA 15.4 W 0.44 - 12.95 W

1 Optional 8 - 13 mA 4.0 W 0.44 - 3.84 W

2 Optional 16 - 21 mA 7.0 W 3.84 - 6.49 W

3 Optional 25 - 31 mA 15.4 W 6.49 - 12.95 W

4 Optional 35 - 45 mA 15.4 W reserved

Table 3-13 Power on Ethernet (PoE) performance classes

The power supply is fed via an active source to a passive IEEE 802.3af-compliant terminal device.

The IEEE 802.3af defines 3 operating modes for the power supply via different wire pairs:

• Endpoint PSE, operating mode A• Endpoint PSE, operating mode B• Midspan PSE, operating mode B

Operating mode A

In operating mode A, the power is fed via the pairs 1/2 and 3/6 using the ‘Phantom Feed’ method. Thus, with Ethernet and Fast Ethernet the pairs 4/5 and 7/8 remain free.

This operating mode is particularly suitable for Gigabit Ethernet, because all 4 pairs are required for the transfer of data.

Operating mode B

In this operating mode, the power is fed separately from the data via the pairs 4/5 and 7/8; the data is fed via the pairs 1/2 and 3/6. Because no pairs remain free, this operating mode is not suitable for Gigabit Ethernet.

The difference between ‘Endpoint PSE, operating mode B’ and ‘Midspan PSE, operating mode B’ is a question of the voltage source. Whereas the switch or another Ethernet component is the source of power for the ‘Endpoint PSE, operating mode B’, an external device supplies the power for ‘Midspan PSE, operating mode B’.


For all operating modes, standardised terminal devices must be equipped with a passive, resistive circuit. This circuit serves various purposes:

• The active source identifies the passive terminal device• The operating mode is recognised• The necessary performance class is recognised.

A PoE solution will only supply power, if a corresponding terminal device is recognised. That avoids damage should a non-standard terminal device be connected.

At present, there are few fields of applications for this technique. However, developments in this field will result in an increased use of this technique in industry. For example, conceivable applications include control of sensors, monitoring of processes or systems by means of cameras or handling of alarms.

3.10 Connectors

Straightforward on-site handling of the termination technology is a major criterion for use in industry. Moreover, it is not just the cable that determines the quality and reliability of data transfers. Connectors and other non-permanent connections also play a major role regarding the susceptibility of networks to faults.

RJ45 and M12 connectors in protection classes IP 20 and IP 65 / IP 67 are available for use in industry and Industrial Ethernet. In particular, RJ45 connectors with different ‘mating faces’ as specified in the IEC 61 076-3-106 enjoy widespread use.

These connectors are easy to assemble on site using standard tools.

Figure 3-34 Possible connectors for Industrial Ethernet from HARTING

94

We should also mention the Industrial Twisted Pair D-SUB connectors to DIN 41 652, available in 9- or 15-pole versions. Connected with the twisted-pair cables by means of screw connections, these connectors are mostly available with metal housings. However, as they generally only play a minor role we will not be taking a detailed look at them within the framework of this book.

Connectors for IP 20

When housed in switchgear cabinets, connectors are used that are fully compat-ible with connectors used in office communications. Theoretically, it would be possible to use ‘normal’ office cables with RJ45 connectors.

However, greater demands are generally placed on IP 20 connectors used in industrial applications. For example, the PROFINET guidelines define also the requirements for connections utilising RJ45 connectors as protection class IP 20.

Figure 3-35 Connectors for Industrial Ethernet in IP 20

As an example, the following image demonstrates the use of connectors with protection level IP 20 in a switchgear cabinet.

Figure 3-36 HARTING RJ Industrial® connectors to IP 20 in use at the Stadler Rail Group, Switzerland (source: HARTING)

Connector for IP 65 / IP 67

In particular, special account must be taken of the industrial demands placed on connectors destined for use outside of the switchgear cabinet. Connector types RJ45 sealed to IP 65 or IP 67 are used in such applications. Special designs can provide protection levels to IP 68.


The M12 circular connector is a further variant. Utilised are the shielded, 4-pole variants with D-coding as included in IEC standards by the DKE for Industrial Ethernet (DKE = German Commission for Electrical, Electronic & Information Technologies).

A third variant is the use of special connectors for fibre-optic cables. In accord-ance with PROFINET Installation Guidelines, for example, the ISO/IEC11801-compliant connection of fibre-optics with an Ethernet component is preferably performed using a special connector system as specified in the IEC 60 874-14.

However, utilisation of fibre-optics is not widespread under Industrial Ethernet so that in the following descriptions a more detailed look will be taken at the conventional connectors RJ45 and M12 with D-coding.

The following provides an overview of the individual connectors with their different types of connections, in which standards they are specified and which user organisations support these types of connectors.

Connectors Specified in Supported by User organisationType Method

RJ45 Bayonet coupling IEC 61 076-3-106 variant 1

IAONAODVA

Snap-in connection IEC 61 076-3-106 variant 2

Screw terminal IEC 61 076-3-106 variant 3

Push Pull connection IEC 61 076-3-106 variant 4

PNO

Connection with locking clamp

IEC 61 076-3-106 variant 5

PNO

Push Pull connection IEC 61 076-3-106 variant 6

IAONAIDAINTERBUS

Connection with locking clamp

IEC 61 076-3-106 variant 7

PNO



Pulse Lock connection IEC 61 076-3-106 variant 10

M12 D-coding

Screw terminal IEC 61 076-2-101 IAONAODVAPNO

Fibre-optics Connection with locking clamp

PNO

Fibre-optic connection IEC 60 874-14 PNO

Table 3-14 Different connectors for Industrial Ethernet in IP 65 / IP 67

96

HARTING has the appropriate connector for all supported Ethernet specifications in its range of supply.

Connector type Ethernet specification *

HARTING connectorIdentification Drawing

RJ45 EtherNet/IPPROFINET

RJ Industrial® IP 67 Data 3A

RJ Industrial® IP 67 Push Pull

RJ Industrial® IP 67 Hybrid

RJ45 Han-Max®

M12 D-coding EtherNet/IPETHERNET PowerlinkPROFINET

M12-L D-coding

Table 3-15 HARTING connectors

* ... Specifications supported by HARTING

The following image demonstrates a typical example of IP 65 / IP 67 connectors used with robots:


Figure 3-37 HARTING RJ Industrial® IP 67 Data 3A connectors in use on robots (source: HARTING)

Which variant in the final analysis will come out on top, RJ45 or M12 connectors, is now more than ever a question of faith. Some experts are of the opinion that the M12 connector will run up against the buffers when 8-wire based Gigabit Ethernet is introduced, because, according to the norm, M12 D-coding is based on a 4-wire cable. On the other hand, other experts point to the fact that the connection technique utilising M12 is already established across the globe in the field of sensors/actuators, and will for that reason come out on top. And yet others are of the opinion that as it all depends on the respective application, that neither of the two variants will be able to gain the upper hand in the near future: M12 will be relied upon when the focus is placed on connecting sensors and actuators, whereas RJ45 connectors will be preferred for vertical communication applications with an eye to the connection with building networks.

When the dust settles, the same will happen as with the introduction of the classic fieldbus system: the user will decide for himself which variant he prefers.

Hybrid connectors

The hybrid connector (data line and power supply combined in one cable) is used where decentralised field devices are connected with both data and power supply via a combined connector. A fully shock-hazard protected connector enables the use of identical connectors at both ends of the cable; the necessity for a male–female configuration eliminated by the integrated protection against accidental touch. The connector in question is the RJ45 to IP 67 for connecting 2- or 4-pair sets of shielded data communication lines for communication, and 4 copper wires for the power supply.

98

Figure 3-38 Hybrid connector

Contact assignment

Contact assignment for RJ45 and M12 connectors are determined in accordance with the corresponding standards:

· RJ45: IEEE 802.3· M12 D-coding: IEC 61 076-2-101

In accordance with the cabling standard (ISO/IEC 11 801:2002), the connectors should be wired to Category 5 compliant, shielded twisted-pair cables with 2x2 or 4x2 cable pairs.

When assembling Ethernet cables, two variants are possible for contact assignments:

1:1 cable

With this cable, the contacts are wired 1:1. That means, for example, that the contact for TD+ on the one connector is connected with the same contact TD+ on the other connector. The contact assignment for such a cable is as follows:

Contact connector 1 Contact connector 2TD + TD +

TD - TD -

RD + RD +

RD - RD -

Table 3-16 Contact assignment for 1:1 cable

Figure 3-39 Contact assignment for 1:1 cable (example: RJ45, 2-pair)

Cross-over cable

With this cable, the contacts for transmitting and receiving are wired crossed over. That means, for example, that the contact for TD+ on the one connector is


connected with the contact RD+ on the other connector. The contact assignment for such a cable is as follows:

Contact connector 1 Contact connector 2TD + RD +

TD - RD -

RD + TD +

RD - TD -

Table 3-17 Contact assignment for cross-over cable

Figure 3-40 Contact assignment for cross-over cable (example: RJ45, 2-pair)

Contact assignment for RJ45, 2-pair

The connectors RJ45 should be wired to twisted-pair cables with 2x2 cable pairs.

Signal Function Wire colour (EIA/TIA 568-B)

Wire colour (PROFINET)

RJ45 Contact number

TD+ Transmission Data + White-Orange Yellow 1

TD- Transmission Data - Orange Orange 2

RD+ Receiver Data + White-Green White 3

RD- Receiver Data - Green Blue 6

Table 3-18 Contact assignment for RJ45, 2-pair (colour code)

Contact assignment, circular connector M12 D-coding

Twisted-pair cables with 2x 2 cores only are used to wire M12 D-coding circular connectors, as these are fitted with 4 pins as standard.

Figure 3-41 Contact assignment for circular connector M12 D-coding (female / male)

100

Signal Function HARAX® Contact number

Wire colour (EIA/TIA 568-B)

Wire colour (PROFINET)

TD + Transmission Data + 1 White-Orange Yellow

TD - Transmission Data - 3 Orange Orange

RD + Receiver Data + 2 White-Green White

RD - Receiver Data - 4 Green Blue

Table 3-19 Contact assignment, circular connector M12 D-coding (colour code)

Contact assignment for RJ45, 4-pair

When wiring 8-wire twisted-pair cables to RJ45 connectors, all 8 wires are wired. However, with Ethernet and Fast Ethernet, only the pairs 2 and 3 have the corresponding functions. The other two pairs (1 and 4) are not recognised or processed by the connected Ethernet device.

1 2 3 54 6 7 8

Pair 1

Pair 4Pair 3Pair 2

Figure 3-42 Contact assignment (pairs) RJ45, 4-pair

Contact assignment

Pair RJ45 Contact number

Signal Function

1 4 Not assigned

5 Not assigned

2 1 TD + Transmission Data +

2 TD - Transmission Data -

3 3 RD + Receiver Data +

6 RD - Receiver Data -

4 7 Not assigned

8 Not assigned

Table 3-20 Contact assignment, wire pairs RJ45 connector


Signal Function Wire colour according to RJ45 Contact numberEIA/TIA 568-A EIA/TIA 568-B

TD + Transmission Data + White-Green White-Orange 1

TD - Transmission Data - Green Orange 2

RD + Receiver Data + White-Orange White-Green 3

Not assigned Blue Blue 4

Not assigned White-Blue White-Blue 5

RD - Receiver Data - Orange Green 6

Not assigned White-Brown White-Brown 7

Not assigned Brown Brown 8

Table 3-21 Contact assignment RJ45 according to EIA/TIA 568 (colour code)

Special conditions for Gigabit Ethernet

In comparison with Ethernet / Fast Ethernet, the principle difference when using Gigabit Ethernet is to be found in the adaptation of the components physically involved with transmissions, or in other words the cable and connectors. Although these components have to be designed for a higher bandwidth, they are ‘downward compatible’ for Ethernet / Fast Ethernet. For this reason, cables suitable for the higher performance of Gigabit Ethernet are mostly laid in new installations.

In the case of copper cables, 4-pair cables only are utilised, because Gigabit Ethernet requires all 8 wires.

Preferably, twisted-pair cables with 4x2 cable pairs should be used.

1 2 3 54 6 7 8

Pair 1

Pair 4Pair 2Pair 3

Figure 3-43 Contact assignment (pairs) RJ45, 4-pair for Gigabit Ethernet

102

Contact assignment

Pair Ethernet / Fast Ethernet Gigabit EthernetRJ45 Pin

Signal Function RJ45 Pin

Signal Function

1 4 RD Not assigned 4 BI_DC+ Receive Data

5 TD Not assigned 5 BI_DC- Transmission Data

2 1 TD Transmission Data + 3 BI_DA+ Transmission Data

2 RD Transmission Data - 6 BI_DA- Receive Data

3 3 TD Receiver Data + 1 BI_DB+ Transmission Data

6 RD Receiver Data - 2 BI_DB- Receive Data

4 7 TD Not assigned 7 BI_DD+ Transmission Data

8 RD Not assigned 8 BI_DD- Receive Data

Table 3-22 Contact assignment for wire pairs, RJ45 connector for Ethernet / Fast Ethernet and Gigabit Ethernet

Figure 3-44 Contact assignment for 1:1 cable and Gigabit Ethernet

Figure 3-45 Contact assignment for cross-over cable and Gigabit Ethernet

1034 Future Prospects

4 Future Prospects

Even as we speak today, Ethernet has already become established in industry. Collision domains are divided up through the utilisation of switches. The special case ‘Switched Ethernet’ fully excludes collisions.

The use of devices and connectors with IP 65 / IP 67 protection levels makes it possible to operate Ethernet in tough industrial conditions, right down to the machine, sensor or actuator. Here the proper cable has a role to play. For longer distances, fibre-optic cables or even wireless connections are available. Wireless LAN can also be utilised should connections with mobile devices be necessary.

Intelligent terminal devices create increasingly complex data packets that conventional fieldbus systems are only able to transmit very slowly. In the future, only Ethernet will be able to guarantee fast and super fast transfers of data.

The continued developments in the hardware sector will also result in falling prices in the manufacture of Ethernet components. The more widespread the use of Ethernet becomes in industry, the more affordable switches, hubs and connectors will be. Observed for years in the office world, this trend can also be perceived in industry.

When all is said and done, there can now be no stopping the triumphant progress of Ethernet in industry, side-by-side with the office world. In saying that, it is not a case of driving out the established fieldbus systems overnight. These bus systems will also retain their right to exist in certain fields. The future world of automation will see Ethernet responsible for the bulk of communication between the individual levels of the automation pyramid (please refer to chapter 1). At the field level in particular, ‘conventional’ fieldbus systems will undoubtedly continue to exist in future.

104

1055 Overview of Modules and Accessories for Ethernet Components from HARTING


5.1 Ethernet devices – Overview of types

HARTING has a variety of Ethernet components in its programme. The user can select between the following products to fulfil application requirements.

Type

Man

agem

ent f

unct

ions

Aut

o-cr

ossi

ng

Aut

o-ne

gotia

tion

Aut

o-po

larit

y

Aut

o-se

nsin

g

Hal

f dup

lex

Full

dupl

ex

Connection options

RJ4

5 to

IP 2

0

RJ4

5 to

IP 6

5 / I

P 67

M12

D-c

odin

g

ESC 67-10 TP05U HARTING RJ Industrial® IP 67 Data 3A

no - - X -

ESC 67-10 TP05U M12 D-coding

no - - - X

ESC 67-10 TP05U Push Pull no - - X -

ESC 67-10 TP05U Han-Max®

no - - X -


no - X X -


no - X - X

EHB 67-10 TP05 RJ Industrial® IP 67 Data 3A

- - - - - - X -

EHB 67-10 TP05 M12 D-coding

- - - - - - - X

HARTING RJ Industrial® Metal Outlet

- - - - - - - - X -

INO M12 D-coding - - - - - - - - - XHARTING RJ Industrial® Outlet Push Pull

- - - - - - - - X -

Table 5-1 Overview of types of components for Industrial Ethernet from HARTING

106

Ethernet switches for direct mounting

Type In accordance with Ethernet specification


• PROFINET


• PROFINET• ETHERNET/IP

ESC 67-10 TP05U Push Pull

• PROFINET


• ETHERNET/IP

Table 5-2 Overview of types of Ethernet switches for direct mounting

‘In-Between’ Ethernet switches



• PROFINET


• PROFINET• ETHERNET/IP

Table 5-3 Overview of types of Ethernet switches for mounting on to exterior cabinet panels from HARTING


Ethernet hubs


EHB 67-10 TP05 RJ Industrial® IP 67 Data 3A


• ETHERNET/IP

Table 5-4 Overview of types of Ethernet hubs to IP 67 from HARTING

Industrial Outlets

Type Housing material

In accordance with Ethernet specification


Metal • PROFINET

INO 67 M12 D-coding Metal • PROFINET• ETHERNET/IP

HARTING RJ Industrial® Outlet Push Pull

Plastic • PROFINET

Table 5-5 Overview of types of Industrial Outlets from HARTING

108

5.2 Mounting options

Type

Wal

l mou

ntin

g -

flat

Wal

l mou

ntin

g -

ver

tical

Mou

ntin

g on

to

top-

hat

mou

ntin

g ra

il

Dire

ct m

ount

ing

onto

hou

sing

pa

nel

Dire

ct m

ount

ing

onto

pan

el o

r gr

ider


Yes Yes Yes - -

ESC 67-10 TP05U M12 D-coding Yes Yes Yes - -

ESC 67-10 TP05U Push Pull Yes Yes Yes - -

ESC 67-10 TP05U Han-Max® Yes Yes Yes - -


- - - Yes Yes

ESC 67-30 TP05U M12 D-coding - - - Yes Yes

EHB 67-10 TP05 HARTING RJ Industrial® IP 67 Data 3A

Yes Yes Yes - -

EHB 67-10 TP05 M12 D-coding Yes Yes Yes - -

HARTING RJ Industrial® Metal Outlet - - - Yes Yes

INO M12 D-coding - - - Yes Yes

HARTING RJ Industrial® Outlet Push Pull - - - Yes Yes

Table 5-6 Mounting options

5.3 Available cable types

Device type Cable typeSTP* UTP** Cat*** Cross-section


Yes Yes 5 AWG 24 / AWG 22



ESC 67-10 TP05U Push Pull Yes Yes 5 AWG 24 / AWG 22

ESC 67-10 TP05U Han-Max® Yes Yes 5 AWG 24 / AWG 22





Table 5-7 Cable types for Ethernet switches

* ... Shielded Twisted Pair

** ... Unshielded Twisted Pair*** ... Category


Device type Cable typeSTP* UTP** Cat*** Cross-section



EHB 67-10 TP05 M12 D-coding Yes Yes 5 AWG 26 / AWG 22



INO M12 D-coding Yes Yes 5 AWG 26 / AWG 22



Table 5-8 Cable types for Ethernet hubs and outlets

* ... Shielded Twisted Pair

** ... Unshielded Twisted Pair*** ... Category

Cable type Cat** RemarksIndustrial Ethernet Shielded Twisted Pair standard cable; 2x2 AWG 22/1 *

5 • PROFINET type A for permanent installation

• For example, for Ethernet switches and outlets with HARTING RJ Industrial®

Industrial Ethernet Shielded Twisted Pair standard cable; 2x2 AWG 22/7 *

5 • PROFINET type B for flexible installation

• For example, for Ethernet switches and outlets with HARTING RJ Industrial®

Industrial Ethernet Shielded Twisted Pair standard cable; 2x2 AWG 22/7 *

5 • PROFINET type C for drag chains

Industrial Ethernet Leitung, two wires twisted to a pair; 4-pairs, symmetrically stranded with foil screen; 4x2 AWG 26/7 *

5 • For flexible installation

Gigabit Ethernet cable, two wires twisted to a pair, and shielded, 4-pairs, symmetrically stranded with screening braid; 4x2 AWG 26/7 *

6 • For flexible installation

Table 5-9 Examples of cable types

* ... Can be supplied by HARTING

** ... Category

Further cable types with a variety of cross-sections can be utilised when they comply with Ethernet specifications.

110

5.4 Connectors

Type

RJ4

5 - I

P 20

da

ta c

onne

ctor

HA

RTI

NG

RJ

Indu

stria

l®

IP 6

7 D

ata

3A

HA

RTI

NG

RJ

Indu

stria

l®

Push

Pul

l

Han

® M

ax

M12

D-c

odin

g


- Yes - - -


- - - - Yes

ESC 67-10 TP05U Push Pull - - Yes - -


- - - Yes -


Yes Yes - - -


Yes - - - Yes


- Yes - - -


- - - - Yes


- Yes - - -

INO M12 D-coding - - - - Yes


- - Yes - -

Table 5-10 Connector variants

111

Annex

112

113List of Standards and Guidelines

Annex A List of Standards and Guidelines

This chapter contains a list of the essential standards and guidelines considered in this manual. No claim is made is made that this list is exhaustive or up-to-date.

The standards and guidelines quoted in this manual are up-to-date at the time of going to press (2005).

Should individual standards in the meantime be withdrawn, up-dated or rewritten, it is the sole responsibility of the user to keep his knowledge as up-to-date as necessary. In particular, IEEE standards are subject to constant revision.

A-1 Standards and guidelines applicable to Ethernet / bus technology

EN standards

EN 50 173-1 Generic cabling systems (international: →ISO/IEC 11 801) – Part 1: General requirements and office areas

EN 50 173-2 Generic cabling systems – Part 2: Industrial area

EN 50 173-3 Generic cabling systems – Part 3: Residential area

EN 50 174-1 Cabling installation – Part 1: Specification and quality assurance

EN 50 174-2 Cabling installation – Part 2: Installation planning and practices inside buildings

EN 50 174-3 Cabling installation – Part 3: Installation planning and practices between buildings

EN 60 950 Information technology equipment - Safety

EN 61 131-2 Programmable controllers – Part 2: Equipment requirements and tests

114

IEEE standards

IEEE 802 Local and metropolitan area networks: Overview and architecture

IEEE 802.1p QoS in Bridges (Multiple Queues)

IEEE 802.2 Local and metropolitan area networks; Specific requirements- Part 2: Logical Link Control

IEEE 802.3 Local and metropolitan area networks; Specific requirements- Part 3: Carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer specifications

IEEE 802.3a 10Base-2 Transmission medium (RG58, BNC)

IEEE 802.3b 10Broad36 Transmission medium (CATV)

IEEE 802.3c 10 Mbit/s Repeater for 10Base-2 and 10Base-5

IEEE 802.3d Fibre Optic Inter-Repeater Link (FOIRL)

IEEE 802.3e 10Base-5: Star topology with Twisted-pair (replaced by 10Base-T)

IEEE 802.3h Layer Management

IEEE 802.3i 10Base-10 (UTP ¾/5 mit 10 Mbit/s)

IEEE 802.3j 10Base-F Fiber-Link (10Base-FL, 10Base-FB, 10Base-FP)

IEEE 802.3k Repeater Management

IEEE 802.3l PICS for 10Base-T Transceivers

IEEE 802.3m Supplement #2 of the standard (sections 1, 7, 8, 9, 10)

IEEE 802.3n Supplement #3 of the standard (sections 4, 6, 7, 8, 10)

IEEE 802.3p 10 Mbit/s MAU Management

IEEE 802.3q Guidelines for the Development of Managed Objects (GDMO)

IEEE 802.3r PICS for 10Base-5

IEEE 802.3s Supplement #4 of the standard (sections 7, 8)

IEEE 802.3t 120 Ω cable to 10Base-T

IEEE 802.3u Fast Ethernet standards 100BaseTX (2 pairs Cat 5), 100BaseT4 (4 pairs Cat 3), 100BaseFX

IEEE 802.3v Shielded 150 Ω cable to 10Base-T (STP)

IEEE 802.3w MAC supplements

IEEE 802.3x Full Duplex (10 / 100 / 1 000 Mbit/s and Auto-negotiation)

IEEE 802.3y 100Base-T (UTP, Category 3 / 4 / 5)

IEEE 802.3z Gigabit Ethernet (1000Base-T / SX / LX / CX)

IEEE 802.3aa 100Base-T supplements (Maintenance)

IEEE 802.3ab 100Base-T (Gigabit Ethernet via UTP; 4 cable pairs)

IEEE 802.3ac Frame format for VLANs (comparision to IEEE 802.1q Tagging)

IEEE 802.3ad Trunking

IEEE 802.3ae Parameters, Physical Layer and Management Parameters for 10 Gbit/s Operation

IEEE 802.3af Powered on Ethernet


IEEE 802.3ak Physical Layer and Management Parameters for 10 Gbit/s Operation, Type 10GBASE-CX4

IEEE 802.5 Local and metropolitan area networks; Specific requirements- Part 5: Token Ring Access Method and Physical Layer Specification

IEEE 802.8 Local and Metropolitan Area Network; Specific requirements- Part 8: Fiber Optic Technical Advisory Group

IEEE 802.11 Local and Metropolitan Area Network; Specific requirements- Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications

IEEE 1 588 Precision clock synchronization protocol for networked measurement and control systems

The respective latest list of IEEE standards is available at:

http://standards.ieee.org

IEC standards

ISO/IEC 11 801 Information technology – Cabling systems for customer premises (see also →EN 50 173)

Guidelines

Guideline ‘IAONA Industrial Ethernet Planning and Installation Guide’ Release 4.0

Guideline ‘Installation guideline PROFINET’ 2.251

116

A-2 Standards and guidelines for devices

EN standards

EN 50 022 Mounting rail. Top-hat mounting rails 35 mm wide for snap-on fitting of devices

EN 50 155 Railway applications - Electronic equipment used on rolling stock

EN 50 081-1 Electromagnetic Compatibility (EMC) – Generic Emissions; Part 1: Residential, Commercial, and Light Industrial Environments

EN 50 082-2 Electromagnetic Compatibility (EMC) – Generic Emissions; Part 2: Heavy Industrial Environments

EN 50 310 Application of equipotential bonding and earthing in buildings with information technology equipment

EN 55 011 Radio disturbance characteristics - Limits and methods of measurement

EN 55 022 Information technology equipment - Radio disturbance characteristics - Limits and methods of measurement

EN 55 024 Information technology equipment - Immunity characteristics - Limits and methods of measurement

EN 60 068-1 Environmental testing – Part 1: General and guidance

EN 60 068-2-6 Environmental testing – Part 2: Tests - Test Fc: Vibration (sinusoidal)

EN 60 068-2-27 Environmental testing – Part 2: Tests - Test Ea and guidance: Shock

EN 60 793-2 Optical fibres – Part 2: Product specifications - General

EN 60 794-2 Optical fibre cables – Part 2: Indoor cables - Sectional specification

EN 60 794-3 Optical fibre cables – Part 3: Sectional specification - Outdoor cables

EN 60 874-1 Connectors for optical fibres and cables – Part 1: Generic specification

EN 61 010-1 Safety requirements for electrical equipment for measurement, control, and laboratory use – Part 1: General requirements

EN 61 373 Rolling stock equipment - Shock and vibration tests – Shock and vibration tests

EN 187 000 Generic Specification: Optical fibre cables

EN 188 000 Generic Specification: Optical fibres

EN 188 100 Sectional specification - Single-mode (SM) optical fibres

EN 188 201 Family specification: Ala graded index multimode optical fibres

EN 188 202 Family specification: AIb graded index multimode optical fibres


IEC standards

IEC 61 000-4-2 Electromagnetic compatibility (EMC) – Part 4-2: Testing and measurement techniques - Electrostatic discharge immunity test

IEC 61 000-4-3 Electromagnetic compatibility (EMC) – Part 4-3: Testing and measurement techniques - Radiated, radio-frequency, electromagnetic field immunity test

IEC 61 000-4-4 Electromagnetic compatibility (EMC) – Part 4-4: Testing and measurement techniques - Electrical fast transient/burst immunity test

IEC 61 000-4-5 Electromagnetic Compatibility (EMC) – Part 4-5: Testing and measurement techniques - Surge immunity test

IEC 61 000-4-6 Electromagnetic compatibility (EMC) – Part 4-6: Testing and measurement techniques - Immunity to conducted disturbances, induced by radio-frequency fields

IEC 61 000-4-8 Electromagnetic compatibility (EMC) – Part 4-8: Testing and measurement techniques - Power frequency magnetic field immunity test

UL standards

UL 508 Industrial Control Equipment – Standard for Safety

UL 1604 Industrial Control Equipment for use in hazardous locations

UL 60 950 Safety of information technology equipment

A-3 Standards and guidelines for connectors

EN Standards

EN 60 352-2 Solderless connections – Part 2: Solderless crimped connections

EN 60 352-3 Solderless connections – Part 3: Solderless accessible insulation displacement connections

EN 60 352-4 Solderless connections – Part 4: Solderless non-accessible insulation displacement connections

EN 60 512 Connectors for electronic equipment

EN 60 603-7 Connectors for frequencies below 3 MHz for use with printed boards - Part 7: Detail specification for connectors, 8-way, including fixed and free connectors with common mating features, with assessed quality

EN 61 076-2-101 Connectors for electronic equipment - Part 2-101: Circular connectors - Detail specification for circular connectors M8 with screw- or snap-locking, M12 with screw-locking for low voltage applications

EN 61 984 Connectors – Safety requirements and tests

118

IEC standards

IEC 60 512 Connectors for electronic equipment – Part 2: Tests and measurements

IEC 61 076-3-106 Connectors for electronic equipment – Part 3-106: Rectangular connectors: Protective housings for use with 8-way shielded and unshielded connectors for frequencies up to 600 MHz for industrial environments

A-4 Standards and guidelines, general

EN standards

EN 50 110-1 / -2 Operation of electrical installations

EN 60 204-1 Safety of machinery – Electrical equipment of machines – Part 1: General requirements

VDE 0100/100 Erection of low-voltage installations

EN 60 529 Degrees of protection provided by enclosures (IP Code)

EN 60 715 Dimensions of low-voltage switchgear and controlgear – Standardized mounting on rails for mechanical support of electrical devices in switchgear and controlgear installations

EN 60 950 Safety of information technology equipment

IEC standards

IEC 60 364 Electrical installations of buildings

IEC 60 364-1 Electrical installations of buildings – Part 1: Fundamental principles, assessment of general characteristics, definitions

IEC 60 364-4-41 Electrical installations of buildings – Part 4-41: Protection for safety - Protection against electric shock

IEC 60 364-4-44 Electrical installations of buildings – Part 4-44: Protection for safety - Protection against voltage disturbances and electromagnetic disturbances

IEC 60 364-5-52 Electrical installations of buildings – Part 5-52: Selection and erection of electrical equipment - Cabling and wiring installations

HD / VDE standards

HD 384.4.41 S2 (VDE 0100 Teil 410)

Erection of power installations with nominal voltages up to 1000 V - Part 4: Protection for safety; Chapter 41: Protection against electric shock

VDE 805 Information technology equipment - Routine electrical safety testing in production

HD 384 (VDE 0100) Erection of power installations

119Annex B Bibliography

Annex B Bibliography

No claim is made that the following list is complete or exhaustive. Many of the following specialist books and documents contain further sources and bibliographies.

For more detailed information about the individual bus systems, please refer to the corresponding websites. The respective addresses are contained in the following chapter.

B.1 General information about fieldbus technology

[FB 1] W. Kriesel, O. Madelung: „AS-Interface, das Aktuator-Sensor-Interface für die Automation“; Carl Hanser Verlag, München, Wien, 1999

[FB 2] R. Becker : „AS-Interface Die Lösung in der Automation“; AS-International Association, Schweinfurt, 2002

[FB 3] G. Schnell: „Bussysteme in der Automatisierungstechnik“; Fried. Vieweg & Sohn Verlag GmbH, Braunschweig, 2000

[FB 4] W. Kriesel, T. Heimbold, D. Telschow: „Bustechnologien für die Automation“; Hüthig-Verlag, Heidelberg, 1998

[FB 5] K. Etschberger: „CAN Controller Area Network“; Carl Hanser Verlag, München, Wien, 2000

[FB 6] W. Lawrenz: „CAN – Grundlagen und Praxis“; Hüthig-Verlag, Heidelberg, 2000

[FB 7] H. Zeltwanger: „CANopen“; VDE Verlag, Berlin, 2001[FB 8] J. Pimentel: „Communication Networks for Manufacturing”; PTR

Prentice-Hall, Englewood Cliffs, USA, 1990[FB 9] B. Reißenweber: „Feldbussysteme“; München, Wien, 1998[FB 10] W. Bonfig: „Feldbussysteme“; Expert-Verlag, Renningen-Malmsheim,

1992[FB 11] R. Busse: „Feldbussysteme im Vergleich“; Pflaum Verlag, München,

1996[FB 12] B. Scherff, E. Haese, H. Wenzek: „Feldbussysteme in der Praxis“;

Berlin, Heidelberg, 1999[FB 13] Phoenix Contact: „Grundkurs Sensor/Aktor-Feldbustechnik“; Vogel

Verlag und Druck, Würzburg, 1997[FB 14] W. Jansen, W. Blome: „INTERBUS: Das offene und durchgängige

Kommunikationssystem“; Landsberg/Lech, 1998[FB 15] M. Popp: „PROFIBUS-DP /DPV1“; Hüthig-Verlag, Heidelberg, 2000[FB 16] D. Reinert, M. Schäfer: „Sichere Bussysteme für die Automation“;

Hüthig-Verlag, Heidelberg, 2001

120

B-2 Industrial Ethernet / network technology

[IE 1] M. Popp, K. Weber: „The Rapid Way to PROFINET“; PNO, Karlsruhe, 2004

[IE 2] M. Hein: „Ethernet – Standards, Protokolle, Komponenten“; Thomson Publishing Company, Bonn, 1995

[IE 3] HARTING manual „Ethernet Switch ESC 67-10 TP05U“; Espelkamp 2004

[IE 4] F. Furrer: „Ethernet TCP/IP für die Industrieautomation“; Hüthig Verlag, Heidelberg, 1998

[IE 5] H. Johnson: „Fast Ethernet – Dawn of a new Network”; Prentice-Hall PTR, Upper Saddle River, N.J., USA, 1996

[IE 6] R. Seifert: „Gigabit-Ethernet“; Addison Wesley Longman, Reading USA, 1998

[IE 7] Hirschmann manual „Grundlagen Industrial Ethernet und TCP/IP“; version 1.0; Neckartenzlingen 2001

[IE 8] HARTING Catalog „Han-InduNet® - Geräte und Komponenten für die Automatisierung“; Espelkamp 2004

[IE 9] IAONA manual „Industrial Ethernet“; Magdeburg, 2004[IE 10] „IAONA Industrial Ethernet Planning and Installation Guide”,

Release 4.0; 2004[IE 11] Hirschmann Pocket Guide „Industrial Ethernet“; Ausgabe 1; 2003[IE 12] Praxis Profiline: „Industrial Ethernet“; Vogel Verlag 2003[IE 13] Praxis Profiline: „Industrial Ethernet“; Vogel Verlag 2004[IE 14] P. Marshall: „Industrial Ethernet – A Pocket Guide”; ISA

(Instrumentation, Systems and Automation Society), USA, 2002[IE 15] Frank J. Furrer: „Industrieautomation mit Ethernet-TCP/IP und

Web-Technologie“; Hüthig, 3. Auflage 2003[IE 16] „LANline spezial“ issue IV / 2003; AWi Verlag, 2003[IE 17] „LANline spezial“ issue IV / 2004; AWi Verlag, 2004[IE 18] P. Schnabel: „Netzwerktechnik-Fibel“; Ludwigsburg, 2004[IE 19] „PROFINET Installation guideline 2.251“; 1998[IE 20] „PROFINET Technologie und Anwendung“; PNO, Karlsruhe, 2002[IE 21] R. Breyer, S. Riley: „Switched and Fast Ethernet”; MacMillan

Computer Publishing, Emeryville, USA, 1996[IE 22] J. Marti, J. Leben: „TCP/IP Networking – Architecture,

Administration and Programming”; PTR Prentice-Hall, Englewood Cliffs, USA, 1994

[IE 23] M. Santifaller: „TCP/IP und ONC/NFS in Theorie und Praxis”; Addison-Wesley Publishing Company GmbH, Bonn, 1993

[IE 24] HARTING „tecNews” issue 11; 2003 [IE 25] HARTING „tecNews” issue 12; 2004

121Annex C Continuative Links

Annex C Continuative Links

No claim is made that the following list is complete or exhaustive. For more detailed information about the individual bus systems, please use search engines or read corresponding technical literature (see also Annex B).

C-1 Links for field bus, general

ArcNet www.arcnet.de

AS Interface www.as-interface.net

Bitbus www.bitbus.org

CAN www.can-cia.de

CANopen www.canopen.de

ControlNet www.controlnet.org

DeviceNet www.odva.org

DIN Messbus www.measurement-bus.de

EIB www.eiba.com

Foundation Fieldbus www.fieldbus.org

INTERBUS www.interbusclub.com

LON www.lonmark.org

ODVA www.odva.org

OPC Foundation www.opcfoundation.org

PROFIBUS www.profibus.com

C-2 Links for Industrial Ethernet

EtherCAT www.ethercat.org

Ethernet/IP www.odva.org

ETHERNET Powerlink ww.ethernet-powerlink.com

Fieldbus.pub Ltd. („The Industrial Ethernet Book“) http://ethernet.industrial-networking.com

Gigabit-Ethernet Alliance www.gigabit-ethernet.org

HSE www.fieldbus.org

IAONA www.iaona.org

Industrial Ethernet Association www.industrialethernet.com

JetSync www.jetter.de

LON www.lonmark.org

Modbus-IDA Group www.modbus-ida.org

ODVA www.odva.org

PROFINET www.profibus.com

SERCOS-III www.sercos.de

safeethernet www.hima.de

Virtual Private Networking Technologies www.vpn.com

122

C-3 Other links

Deutsches Institut für Normung www.din.de

EIA www.eia.or

Fieldbus.pub Ltd. („The Industrial Ethernet Book“) http://ethernet.industrial-networking.com

HARTING Electric GmbH & Co. KG www.HARTING.com

IEEE www.ieee.org

IEEE – list of actual standards http://standards.ieee.org

ISO Standards www.iso.ch

Request for Comments www.ietf.org

Verband Deutscher Maschinen- und Anlagenbauer www.vdma.de

Virtual Private Networking Technologies www.vpn.com

Zentralverband Elektrotechnik- und Elektronikindustrie e.V.

www.zvei.de

123Glossary

Glossary

1:1 cable →Twisted-pair cable by which the cable ends are wired 1:1. That means that each pin on the one end of the cable is connected to the same pin on the other end of the cable (example: TD+ ↔ TD+)

10Base-2 →Ethernet standard for transmitting data at 10 Mbit/s using thin coaxial cables (Thin Wire, Cheapernet). The maximum length of the segments is 185 m.

10Base-5 →Ethernet standard for transmitting data at 10 Mbit/s using coaxial cables (Thick Wire, Yellow Cable). The maximum length of the segments is 500 m.

10Base-FL →Ethernet standard for transmitting data at 10 Mbit/s using →fibre-optic cables. Each connection is created using two fibres. One fibre is used for transmitting, the other for receiving.

10Base-T →Ethernet standard for transmitting data at 10 Mbit/s using →twisted-pair cables (→categories 3, 4 or 5). Each connection is created with two wire pairs. One wire pair is used for transmitting, the other pair for receiving.

100Base-FX →Ethernet standard for transmitting data at 100 Mbit/s using →fibre-optic cables. Each connection is created using two fibres. One fibre is used for transmitting, the other for receiving.

100Base-TX →Ethernet standard for transmitting data at 100 Mbit/s using →twisted-pair cables (→Category 5). Each connection is created with two wire pairs. One wire pair is used for transmitting, the other pair for receiving.

1000Base-LX →Ethernet standard for transmitting data at 1 000 Mbit/s using →fibre-optic cables operating at a wavelength of 1 300 nm. Each connection is created using two fibres. One fibre is used for transmitting, the other for receiving.

1000Base-SX →Ethernet standard for transmitting data at 1 000 Mbit/s using →fibre-optic cables operating at a wavelength of 850 nm. Each connection is created using two fibres. One fibre is used for transmitting, the other for receiving.

Address Resolution Protocol

Please refer to →ARP

Address/port assignment table

Table containing the assignment of →destination addres-ses to the respective →ports on a →switch. This table is created and maintained automatically by the →switch.

Aging Process used to update data, in particular those of the →address/port assignment tables. In this process, an address is marked as ‘old’ once a certain amount of time has elapsed and is then deleted if it is again not recognised at any →port during the next cycle.

American Wire Gauge Please refer to →AWG

Approved use Applicable conditions that fall within the specifications for that type of construction or rated values, environmental conditions and characteristics determined by the manufacturer.

124

ARP Address Resolution Protocol A protocol that ascertains a →MAC address through the →IP address assigned to the station. In this case, each device administers its own ARP table.If the station →MAC address to which it is intended to send a telegram is not contained in the ARP table, the device transmits an ARP request in the form of a →broadcast telegram. The station whose →IP address is contained in this ARP request transmits an ARP reply together with its →MAC address. The station that initiated the ARP request adds the →MAC address to its ARP table, and is then subsequently able to transmit the telegram..

AUI Attachment Unit Interface Term for an →Ethernet interface with a 15-pole D-Sub →connector

Auto-crossing Enables automatic crossing at the →twisted-pair inter-faces of the wires used for transmitting and receiving. This allows the user to utilise 1:1 wired cables and →cross-over cables on an equal basis.

Auto-negotiation Recognises the transmission parameters of the connected device such as speed, duplex mode and flow control at the →port, and automatically sets the corresponding optimum values.

Auto-polarity Function utilised by components in accordance with →10BASE-TX or →100BASE-TX to automatically correct wiring mistakes in →twisted-pair cables that result in polarity reversal of the data signals (RD+ and RD-).

Auto-sensing Enables a device, (for example, a →hub) to detect the maximum possible →transmission rate of a connected station (10 Mbit/s or 100 Mbit/s), and then to transmit and receive at this rate. In the case of →hubs, all →ports operate at the lowest transmission rate detected.

AWG American Wire Gauge The AWG figure describes a cable based on its wire diameter and permissible attenuation. Depending on the cable structure, AWG sizes correspond to metric values as follows: • AWG 22: 0.33 to 0.38 mm² wire cross-section• AWG 24: 0.21 to 0.25 mm² wire cross-section• AWG 26: 0.13 to 0.15 mm² wire cross-section

Backbone Term for the highest-level network of an hierarchically structured installation (for example, in building networks)

Backpressure Function using a →jam signal to simulate a →collision in →Half duplex mode of operation

Bandwidth Please refer to →transmission rate

Bandwidth-length product A characteristic unit of measurement used with →fibre-optic cables that describes the factor for determining the maximum distance that can be covered when utilising →multi-mode fibres.

125Glossary

Bayonet Fibre Optic Connector

Please refer to →BFOC

Bayonet Neill Concelmann Please refer to →BNC

BFOC Bayonet Fibre Optic Connector Widely used →connector for →fibre optic cables with bay-onet lock; also known as ST connector. BFOCs are the only →connectors standardise for 10 Mbit/s →Ethernet.

Blocking Please refer to →switch, blocking

BNC Bayonet Neill Concelmann Widely used →connector for coaxial cables and devices under →10Base-2

BootP Bootstrap Protocol A protocol that supplies a station connected to an →Ethernet network with a permanent IP address based on its →MAC address.

Bootstrap Protocol Please refer to →BootP

Bridge Component used in →Ethernet networks operating on layer 2 of the →OSI Reference Model to connect two sub-networks of the same kind. Based on their →MAC address, data packets are transmitted from one sub network to another.

Broadcast Term for transmitting a (unreceipted) message to a group of unspecified recipients.

Broadcast telegram Data packets addressed to all network nodes. →Hubs and →switches are transparent for broadcast telegrams.

Burst Brief increase of network load due to flood of data or gush of signals

Bus Common transmission line connecting all components. Topologies usually have two ends, ring topology being the exception. Communication is based on a protocol.

Bus system A bus system formed by all components being physically connected via a →bus.

Cable Together with the sheath, one or more insulated →conductors. These →conductors can belong to the same type and to the same →category as well share a joint shielding.

Carrier Sense Multiple Access with Collision Detection

Please refer to →CSMA/CD

Category →Cable is categorised according to its electrical transmission and high-frequency characteristics.

CENELEC Comité Européen de Normalisation Electrotechnique European Committee for Electrotechnical Standardisation responsible for harmonisation of electrotechnical standards within the European Union.

Cheapernet Please refer to →10Base-2

Class Classification of point-to-point transmission channels according to their transmission and high-frequency characteristics.

126

Coding pin Ensures the correct alignment of the both mating →connectors

Collision Occurs when several stations attempt to transmit simul-taneously over the network. This is detected by the →CSMA/CD mechanism.

Collision domain The →CSMA/CD access procedure restricts data packet transmission time between two components. Depending on the →transmission rate, this results in a spatially restricted network: the collision domain. The maximum extension of a collision domain is 4250 m at 10 Mbit/s (→Ethernet) and 412 m at 100 Mbit/s (→Fast Ethernet). →Full duplex mode connections allow extensions exceed-ing these limits, because no →collisions can occur. The use of →switches is a pre-condition.

Connection Mirroring This function makes it possible for a copy of data trans-mission between two →ports of a →switch to be made available to other →ports, for example, for analysis purposes.

Connector Component part enabling the electrical connection of the electric cable; designed to create a disconnectable electrical connection with a suitable mating connector. A connector consists of a housing, →contact inserts and contact elements

Contact insert →Insert for accommodating and positioning of contact elements in the →connector.

Conductor Arrangement of wires, insulation and accessories to conduct electrical energy from one point of a network to another.

CRC Cyclic Redundancy Check Term for algorithm used to detect and correct errors in bit-oriented protocols. The unit used for error recognition and correction is called the ‘Haming Distance’.

Cross-over cable →Twisted-pair cable whose ends are wired ‘crossed-over’. In other words, the pins for transmissions (TD+) on the one end of a cable are connected to the pins for receiving (RD-) of the respective wire pair on the other end of the cable (example: TD+ (1) ↔ RD+ (1))

CSA Canadian Standards Association Canadian institute for quality assurance of technical products

CSMA/CD Carrier Sense Multiple Access with Collision Detection Network access method by which the component checks if the network is free for transmissions (Carrier Sense). Simultaneous ‘Collision Detection’ checks are made at the beginning of transmissions to ascertain if another node has also began to transmit. If this is the case, a →collision occurs. As a result, all participating network components stop transmitting, and wait a randomly determined period of time before resuming transmissions.

127Glossary

Cut-Through →Switch operating mode for forwarding telegrams as soon as the destination address is recognised. The lower latency time in comparison with the →Store and Forward mode is the major advantage of this mode; the disadvantage is that faulty telegrams are also forwarded. Speed synchronisation between the individual segments is not possible with this operating mode.

Cyclic Redundancy Check Please refer to →CRC

DA Destination Address →Destination addressing the →Ethernet telegram

Data Terminal Equipment Please refer to →DTE

DCP Discovery and Configuration Protocol Protocol for reading of the name, the →IP address and other parameters of a network station. Individual stations can be found out in the netwok via an →Identify service.

Delay Delay, caused by the running time of transmission or by internal time delays of a network component

Destination address Device →MAC address in an →Ethernet telegram that is clearly assigned to a →port of a →switch in the →address/port assignment table.

Deterministic system A system by which the timing process can be planned and therefore predicted.

DHCP Dynamic Host Configuration Protocol Protocol for allocating temporary →IP addresses taken from an agreed range.

The protocol automates and centralises the →IP settings of individual devices on the network. Network devices in a network intended for integration in a network or Internet by means of the Internet protocol (→TCP/IP) require various basic settings, without which communication would not be possible. This process can be carried out via a DHCP server without user assistance, because the DHCP server is acquainted with the settings and can pass these on to the device. Without a DHCP server, the user has to carry out the settings manually, and re-enter these each time the network is changed. This process is performed automatically each time when a DHCP server is utilised.

DIN Deutsches Institut für Normung German Institute for Standardization

Dispersion Differences in propagation times with →fibre-optic cables that can lead to degradation of the pulses of light fed into the →fibre-optic cable.

DKE Deutsche Kommission Elektrotechnik Elektronik Informationstechnik German Commission for Electrical, Electronic and Information Technologies (of DIN and VDE).

DNS Domain Name System Name of a system that maps host names, addresses in plain text and →IP addresses to one another. DNS servers or files designated as ‘hosts’ can serve as the source of data for implementation purposes.

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Domain Name System Please refer to →DNS

DSC Duplex Straight Connector →Connector variant widely used for →fibre-optic cables.

DTE Data Terminal Equipment Term used for terminal equipment in an →Ethernet network.

Duplex Straight Connector Please refer to →DSC

Dynamic Host Configuration Protocol

Please refer to →DHCP

Earth Conductive mass of earth whose electrical potential is, in accordance with the relevant agreements, zero at all points.

EHB 67-10 TP05 Type designation for an →Ethernet →hub from HARTINGEHB →Ethernet →hub 67 →IP 67 10 Housing designTP →Twisted-pair05 5 →ports

EIA Electronic Industries Association American electronic industries alliance whose standards are entitled RS (Related EIA Standard) – for example, →RS 232, →RS 485.

Electromagnetic compatibility

Please refer to →EMC

Electrostatic Discharge Please refer to ESD

EMC Electromagnetic Compatibility Refers to the capability of a piece of →electrical equip-ment in a given (electromagnetic) environment to function flawlessly without it having a negative influence on its surroundings.

EN European Norm Please refer to →CENELEC

Equipment, electrical All components used for creating, converting, transmitting, distributing and use of electrical energy.

ESC 67-10 TP05U Type designation for an →Ethernet →switch from HARTINGESC →Ethernet →switch 67 →IP 67 10 Housing designTP →Twisted-pair05 →portsU →unmanaged

ESD Electrostatic Discharge Electrostatic discharges that can lead to short and irregular disturbances in electronic devices or to the destruction to electronic components.

129Glossary

Ethernet Network transmission system developed and standardised by DED Intel and Xerox; characterised by the following components:• Baseband technology• →CSMA/CD – access method• Variable packet lengths between 64 and 1518 bytes• Transmission rates from 10 Mbit/s• Logical bus topology• Coaxial cableThe subsequent standard, IEEE 802.3, ensured integra-tion in the →ISO/OSI Reference Model and extended the physical layer and transmission media by the use of repeaters and implemented applications operating via →fibre-optic cables, broadband and →twisted-pair cables. In addition, protocols from layers 3 and 4 are often called upon. Today, Ethernet is often used as a generic term, without differentiating between the various →transmission rates of 10 Mbit/s, 100 Mbit/s (→Fast Ethernet), 1000 Mbit/s (Gigabit-Ethernet).

Ethernet packet Term for an →Ethernet data packet comprising:• Preamble (8 bytes)• Destination address(6 bytes)• Source Address (6 bytes)• Length/Type (2 bytes)• Data field (64 to 1518 bytes)• Check (4 bytes)

EtherType Identification of an →Ethernet →frames by a number of 16 bits assigned by the →IEEE. For example, →IP uses EtherType 0x0800, →PROFINET 0x8892 (both itemisations are hexadecimal)

Fast Ethernet Fast data network specified in 1995 in the IEEE 802.3. Important parameters: transmission rate 100 Mbit/s; variable packet lengths: 64 to 1522 byte (with optional 4-byte tag field).

FCS Frame Check Sequence An array of bits required for data security purposes in bit-oriented protocols. The device transmitting the telegram calculates a checksum in accordance with an established algorithm; the checksum is then added to the end of the telegram (check field). The recipient of the data telegram also creates a checksum from the data received using the same algorithm. The telegram was transmitted without any errors if both checksums match.

FCX Please refer to →Full duplex mode

FDDI Fibre Distributed Data Interface A standard for data networks covering layers 1 and 2 of the →ISO/OSI Reference Model. FDDI was originally based on a double-ring technology specifying →fibre-optic cables as transmission medium.

Female connector Contact element by which the inside surface is designed to make suitable contact with a →male pin.

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Female insert →Insulated housing used for accommodating and positioning of (contact) →female insert in the →connector.

Fibre optics Please refer to →fibre-optics cable

Fibre-optics cable In contrast to electrical transmission technology that, for example, uses →twisted-pair cables for data transmis-sions, optical transmission technology utilises glass or plastic as the transmission medium. Fibre-optic cables are available in multi-mode and single-mode (mono-mode) fibre versions.

Filters →Switches filter the data traffic based on the source and destination address contained in a data packet. A →switch will only relay an incoming data packet to the →port to which the terminal device with the corresponding →destination address is connected.

Firmware Software code containing all device functions. This code is stored on a PROM (Programmable Read Only Memory), and remain stored after the device is turned off. It is possible for the user to up-date the firmware when a new software version becomes available (firmware upgrade).

Flow Control This function discards data packets or signals connected stations informing them to stop transmitting if a →port becomes overloaded. In →Half duplex mode, this signal is generated by simulating a →collision, and in →Full duplex mode by transmitting a special ‘pause’ signal.

Frame Data packet containing the header, data and checksum; in the case of →Ethernet, a frame consists of between 64 and 1518 bytes (1522 with →VLAN tag).

Frame Check Sequence Please refer to →FCS

FTP File Transfer Protocol A protocol on layer 5 of the →ISO/OSI Reference Model, used for transporting files.

Full Duplex Please refer to →Full duplex mode

Full duplex mode A →switch simultaneously transmits to and receives signals from the same ?port.

GARP Generic Attribute Registration Protocol Family of protocols for exchanging parameters between →switches on layer 2 of the ISO/OSI Reference Model. Presently available are the protocols →GMRP and →GVRP.

Gateway A device operating above layer 2 of the →ISO/OSI Reference Model converting and translating the protocols of the various networks.

Gigabit Ethernet Term for a very fast data network that has been standardised in the IEEE 802.3 since 1999. It is based on a →transmission rate of 1000 Mbit/s with a variable packet length of 64 to 1518 bytes.

131Glossary

GMRP GARP Multicast Registration Protocol →IEEE 802.1p compliant protocol allowing dynamic signing-on and off of stations belonging to →multicast groups. →switches supporting GMRP forward the →multicast telegrams only to those →ports to which stations belonging to the corresponding →multicast group are connected.

Ground An electrically conductive part, which is conductively connected to the earth mass via the earthing system.

GVRP GARP VLAN Registration Protocol →Switches are able to utilise this protocol to exchange information with →VLANS. If a →VLAN is set up on a →switch, then this information is transmitted by the →switch to all other →switches on the network. As a result, other →switches can, for example, declare the →port, at which the information was received, a station of this →VLAN.

Half duplex Please refer to →Half duplex mode

Half duplex mode The →switch can only receive or transmit at any given time. →collision recognition is active in half duplex mode.

HARTING RJ Industrial® RJ45 IP 67 Data 3A

HARTING connector for →twisted-pair cables with →RJ45 connection technology (4- or 8-wire) sealed to degree of protection →IP67 in a standard housing of the type Han® 3 A.

HCS® Hard Clad Silica →Fibre-optic cables with an optical core made of quartz glass and optical cladding made of a special, patented sheath of plastic.(Registered trademark of Spectran Corporation)

HDX Please refer to →Half duplex mode

Header Part of an →Ethernet packet heading the actual data field containing addresses, packet number, type and other information.

HIPER Ring Name of a redundancy procedure based on the concept of a ring-type network structure. Components supporting HIPER RING networks are connected to each other within such a ring via their ring ports. A redundancy manager controls the ring and prevents telegrams flying around.

Hops Term for the maximum number of →routers that a data packet is allowed to pass through on its way through the network. The number of hops within a connection is not an indication of the quality of that connection. For example, a connection with 8 hops can be faster than one with 5 or 6 hops.

HSRP Hot Standby Routing Protocol Protocol for controlling redundant →routers

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Hub Component on level 1 of →ISO/OSI Reference Model that regenerates the amplitude and shape of the incoming signal before forwarding it to all ports. Some hubs (for example, from HARTING) generate a →jam signal when they detect a collision. Thus, these hubs can also be assigned to layer 2 of the →ISO/OSI Reference Model.

Hybrid cable →Cable containing data lines and 2 to 4 wires to supply power to decentralised field devices.

Hybrid connector →Connector that can be terminated to a →hybrid cable (data line and power supply in a single connector).

IAONA Industrial Automation Open Networking Alliance An alliance of leading manufacturers and users of automation systems wishing to establish →Ethernet as the standard application in all industrial environments on an international basis as well as striving to achieve uniform, interface-free communication across all company levels of plant, process and building automation. For more information, visit www.iaona-eu.com

ICMP Internet Control Message Protocol Protocol that reports failures and errors during the transmission of →IP packets (for example, through the →’Ping’ command).

ID Identifier

IDC connection Solder-free connection created by pressing the individual wires into precisely defined slits in the terminal; the blade-like slit sides displace the insulation from the wire as well as deforming it at the same time to create the connection.

IDC connection technology

Insulation Displacement Connection Please refer to →IDC connection

Identify Identification service of →DCP. For example, a station with a particular name can be invited to answer.

IEC International Electrotechnical Commission An international standardisation committee

IEEE Institute of Electrical and Electronics Engineers Standardisation committee for →LANs providing the most important standards 802.3 for →Ethernet and 802.1 for →switches.

IETF Internet Engineering Task Force Group responsible for technical matters concerning the Internet.

IFG Inter Frame Gap Unit of measure for the minimum distance between two data packets.

IGMP Internet Group Management Protocol Name of the layer-3 protocol that informs routers immediately adjacent to stations and →routers of their affiliation to →multi-cast groups.

133Glossary

IGMP Snooping Internet Group Management Protocol Snooping A function with which →switches examine IGMP packets and assign device membership of a →multi-cast group to the respective →port. This allows →multi-casts to be specifically communicated to segments in which members of a group are located.

IGP Interior Gateway Protocol Classification of routing protocols used for exchanging information between →routers within an autonomous network. Protocols utilised include IGRP, RIP und OSPF.

Impedance Input resistance of an infinitely long wire or of a closed wire with the characteristic resistance.

Industrial Ethernet Term used for →Ethernet in automation engineering. Due to the industrial environments, the network components have to fulfil higher demands in respect of increased temperature ranges and increased demands for availability and network safety.

Insert Part of a →connector, mostly identical with the →contact insert

Instructed person (to DIN EN 50 110-1)

A person instructed by a →skilled person (electrician) to a sufficient degree, who is then able to avoid danger arising from electricity. (IEV 826-09-02, modified)

Insulation stripping length Length of insulation to be stripped from the →cable or individual wires.

Insulation voltage Also known as rated insulation voltage: refers to the insulation within an electrical circuit, between electrical circuits as well as between active components and conductive parts. This is the voltage to which dielectric tests and creepage distances refer. Under no circumstances is it permitted for the operating voltage to be greater than the insulation voltage. It must be assumed for devices without a declared insulation voltage that the highest operating voltage is the insulation voltage.

Inter Frame Gap Please refer to →IFG

Interference, capacitive A capacitive (electrical) coupling occurring between two wires carrying differing potentials. For example, signal cables routed in parallel or static discharges are typical sources of interference.

Interference, inductive An inductive (magnetic) interference occurring between two live, current carrying wires. The magnetic effect resulting from the currents induces an interference voltage. For example, motors, parallel routed network cables and HF signal cables are typical sources of interference.

IP International Protection Protection class for devices and equipment according to EN 60 529 and IEC 60 529.

134

IP Internet Protocol Transmission protocol on layers 3 and 2 of the →ISO/OSI Reference Model. The following versions are presently valid:·• IPv4: Version 4 4 address bytes• IPv6: Version 6 6 address bytes

IP address Logical address allocated by the network operator to a station on layer 3 of the →ISO/OSI Reference Model. Under →IPv4 (4 bytes) the address is written in decimal notation separated by a full stop (example: 198.178.002.001). This labels the addresses for the network (network ID) and the address area of the terminal device (host ID). Because →IP addresses must be unique, public network addresses are administered by a central organisation. Local (‘private’) →IP addresses are issued by the administrator of the respective local network.

Caution! Do not confuse with the →MAC address!

IP address, dynamic Contrary to a static →IP address, the dynamic →IP address is temporarily assigned through the →DHCP protocol.

IP address, static In contrast to a dynamic →IP address, this is a permanently set →IP address.

IPv4 Internet Protocol Version 4 IPv4 has an address volume of 4 bytes. Please refer to →IP

IPv6 Internet Protocol Version 6 IPv6 has an address volume of 6 bytes. In addition, it differs as far as the structure of the header is concerned and how it categorises networks in address types instead of classes. Please refer to →IP

ISO International Standardization Organization World-wide standardisation committee

ISO/OSI Reference Model Model for describing communication within a network. The functionality is specified in 7 levels. The lower (physical level) provides the interface to the physical transmission medium.

ITU-T International Telecommunication Union –Telecommunication Standardization Sector Standardisation committee for telecommunications

Jabber Relates to abnormal Ethernet frame transmissions. The data packets triggering the situation are generally too long (more than 1518 bytes). A malfunctioning →Ethernet card also be the cause of the problem. Jabber can lead to loss of data for all network users.

Jam signal Short code sequence that a →network node transmits in a →CSMA/CD network when a →collision is detected and the data transmission has been discontinued. This signal informs the other →network nodes about the →collision, so that they desist from attempting transmissions.

135Glossary

Jitter Term for the fluctuation in the timing of the signal edge

LAN Local Area Network Local network, for example, →Ethernet

Last Significant Bit Please refer to →LSB

Latency Term used for the time difference between receiving and forwarding of data. Latency is generally measured as the time between receiving the last bit and transmission of the first bit.

Link aggregation Term used for a function that combines up to 4 →ports operating the same →transmission rate to a virtual →port. Thus, redundancy is created should a connection fail. This function is also known as →trunking.

Link Logical connection between a single or several user(s) using network services.

Local Area Network Please refer to →LAN

LSA+ Lötfrei Schraubfrei Abisolierfrei Universal usuable termination technology of wires by a special →IDC connection

LSB Last Significant Bit Least significant bit within a sequence of bits on →Ethernet

M12 D-Coding Circular connector from HARTING for →twisted-pair cable with →IDC technology.

MAC Media Access Control Term for a sub-layer of layer 2 of the →ISO/OSI Refer-ence Model. This sub-layer polices access to the shared transmission medium. To do so, it can utilise processes by which either several stations with equal rights compete for access (for example, →CSMA/CD) or in which no collisions occur at all, for example, ‘token ring’.

MAC address Media Access Control-Address Unalterable, world-wide unique hardware address allocated by the manufacturers’ of devices operating on an →Ethernet network; assigned to a →port of a →switch in the →address/port assignment table as the →destination address.

MAC Media Access Control

Parts of a network protocol that manage access to the transmission medium; this eases data exchange between network nodes.

Male Contact element by which the outside surface is designed to make suitable contact with a →female connector.

Male insert →Insert used for accommodating and positioning of (contact) →male inserts in the →connector.

Managed Please refer to →switch, managed

Mass All interconnected inactive components that do not take on a dangerous touch potential in the case of a fault.

136

MDI port Medium Dependent Interface-Port In accordance with →IEEE standards, MDI is the term used for the →twisted-pair interface of a device to →10BASE-T (or →100BASE-TX). By utilising this →RJ45-→port, It is possible for the →hub to be connected to a networking unit (for example, →switch) using →1:1 cable.

MDI-X Port Term for the MDI interface that crosses incoming and outgoing signals.By utilising a corresponding →RJ45- →port, it is possible for the →switch to be connected to any unit with a standard interface using →1:1 cable (for example, a →server or a →router).

Mean Time Between Failure

Please refer to →MTBF

Media Access Control Please refer to →MAC

Media converter A device operating on layer 1 of the →ISO/OSI Reference Model that converts signals between different media, for example, optical to electrical.

MII Media Independent Interface Term for an interface complying with the →ISO/OSI Refer-ence Model operating between the physical layer (1) and the data link layer (2) and supports →100BASE-TX, →100BASE-T4, →100BASE-FX and →10BASE-T.

Mono-mode fibre Please refer to →single-mode fibre →fibre-optic cable

Most Significant Bit Please refer to →MSB

MSB Most Significant Bit Most significant bit within a sequence of bits on →Ethernet

MTBF Mean Time Between Failure Considered probability denoting expected time between failures.

Multicast filtering Term for process that enables a →switch to selectively forward →multicast telegrams. Otherwise, multicasts are forwarded to all →ports on a →switch.

Multicast telegram Data packet addressed to all devices of a group. This offers the possibility of addressing a given group via just one address.

137Glossary

Multi-mode fibres →Fibre-optics distinguished by core diameters of a similar size. The typical core diameter of step-index fibres made of glass is 100 µm, 200 µm for PCS/→HCS® fibres and 980 µm with →POF fibres. On the other hand, gradient index fibres typically have a core diameter of 50 and 62.5 µm. Due to the relatively large core diameter, the light disperses in multi-mode fibres along different paths (several modes). The distance to be bridged along a multi-mode fibre depends on several factors: the rated data of the fibres, the link budget as well as the attenuation resul-ting from →connectors, splices and other components.Signal bandwidths:• Ethernet = 10 MHz,• Fast Ethernet = 125 MHz and• Gigabit Ethernet = 1.25 GHz

Network management Administration, configuration and monitoring of network components. The management agent in the component to be managed communicates with the management station (PC) by means of the →SNMP management protocol.

Network management station

Station on which the →SNMP management software is operated. The network management station is utilised by the network administrator to monitor the network.

Network mask The network mask marks all of the bits contained in an IP address identifying the network and sub-networks. Binary code:• IP address 10010101.11011010.00010011.01011010• Network mask 11111111.11111111.11111111.00000000• Sub-network 10010101.11011010.00010011.00000000Decimal code:• IP address 149.218.19.90• Network mask 255.255.255.0• Sub-network 149.218.19.0Available address range:• Station addresses 149.218.19.1 to 149.218.19.254• Broadcast address 149.218.19.255Please refer to →IP address

Network nodes Term for network elements such as →hubs, →switches and →routers through which various data transmission paths converge.

Network segmentation Network segmentation restricts →collision domains enabling improved performances in →Ethernet networks. Network segmentation can, for example, be achieved by utilising →switches. Please refer to →segmentation

NEXT Near End Cross Talk A form of feed-over, in which the signals from components at the same end of a →twisted-pair cable superimpose on one another.

Non-blocking Please refer to →switch, non-blocking

Octet Term of →IEC 61 158. An octet includes exactly 8 bits.

138

OSI Open System Interconnect International programme for standardisation founded by →ISO and →ITU-T to create standards for data networks that guarantee compatibility of devices from different manufacturers. Please refer to →ISO/OSI Reference Model

OSPF Open Shortest Path First Name of a routing protocol. OSPF uses the information supplied by →routers concerning the topology of the network to determine the shortest path between the →routers. A pre-condition for this function is that each →router creates a routing table in which the actual →topology of the network is stored. The routing tables are constantly updated by the →routers immediately informing adjoining →routers of changes to the topology. The advantage offered by OSPF in comparison with →RIP is in the speed and improved network load distribution.

OUI Original Unique Identifier Term for the most significant 3 bytes of the →MAC address.

Patch cable Term for →cable with a maximum length of max. 5 m used for connecting →Ethernet components within a room (19“ rack, switchgear cabinet). Patch cables are mostly used in conjunction with patch fields.

PCF Term for a →fibre-optic cable whose optical core is made of quartz glass and whose optical sheath is made of a layer of polymer.

PDU Protocol Data Unit Term for a data packet compiled on a layer of the →ISO/OSI Reference Model that is passed to the layer below through a service access point (→SAP).

Personnel, qualified According to EN 50 110-1, →skilled personnel (electrician) and →persons properly instructed by an electrician count as qualified personnel.

Ping Packet Internet Groper A program that tests the connection between two →IP addresses. This determines if a station on a given network is active, and how good the connection to it is.

Plastic Optical Fibre Please refer to →POF

PoE Power of Ethernet Technology defined in IEEE 802.3af for carrying the voltage supply via →Ethernet cabling. Depending on the operating mode, power is supplied either via the free wire-pair of an →Ethernet cable or via the wire-pair used for data transmissions.

POF Plastic Optical Fiber Term for a →fibre-optic cable whose optical core is made of quartz glass and whose optical sheath is made of synthetic material. POF fibres typically have a core diameter of 0.98 mm.

Port →Ethernet connection of a →switch to which one or several devices can be connected.

139Glossary

Port Mirroring Function for copying of incoming and outgoing data at a →port of a →switch to a different →port, where it can be analysed using a network analysing device.

Port security Function that protects against unauthorised access to the network. →Switches supporting this function provide the option of determining for each →port from and to which terminal device data can be received and forwarded. The check is made based on the →MAC addresses of the connected devices. If a device is connected to a →port where the →MAC address is not registered, the →port can be shut down automatically.

Port trunking Please refer to →link aggregation

Potential equalization Electrical connection that achieves the same or approxi-mately the same electrical potential for components of equipment and separate conductive components.

pps Packets per Second Unit of measurement used for switching speeds.

Prioritising Prioritised data transmissions of →Ethernet packets are switched as a matter of priority in accordance with defined criteria. Such →Ethernet packets are labelled via the →tag field on layer 2 and in the →TOS field in layer 3 of the →ISO/OSI Reference Model.

PROFINET A network concept defining communication from the field to the process control level that includes PROFIBUS and →Ethernet as well as a model for plant-wide engineering. For more information, log onto: www.profibus.com.

Protective earth (PE) Cable required for several protective measures against dangerous shock currents in order to create an electrical connection to one of the following components:• Framework of electrical equipment• Separate conductive components• Main earthing terminal / earth• Earthed point of power source or artificial neutral point

Protocol Data Unit Please refer to →PDU

PTP Precision Time Protocol Protocol according to →IEEE 1588 for description of a method to exactly time synchronisation

PTP Master Station acting as timer in a network segment

PTP-Slave Station in a network segment, which is synchronised by a →PTP-Master synchronisiert wird.

QoS Quality of Service Term for a range of factors that influence the quality of a network. These factors include, for example, network down times, delay times, stability of connections and many more. Definitions of QoS vary widely.

Quad Cable Star quad A →cable type, whose both wire pairs are twisted together. This results in a hihger electromagnetic compatibility.

Quality of Service Please refer to →QoS

140

Railway standard (DIN EN 50 155)

Standard specifically concerned with operating conditions of electronics equipment on rolling stock

RAM Random Access Memory Term for a volatile memory

Random Access Memory Please refer to →RAM

Rapid Spanning Tree Protocol

Please refer to →RSTP

RARP Reverse Address Resolution Protocol A protocol that supplies the assigned static →IP address to a →MAC address

Real-time From the point of view of a system, this means that delay times in communication have no negative effects or disrupting influences on a process.

Real-time Protocol Please refer to →RTP

Redundancy Availability of equipment not required for basic functions. Should a piece of equipment fail, the additional (redundant) equipment can perform its function.

Redundancy manager Term for →HIPER ring network components responsible for monitoring the ring and for activating redundant connections when an interruption in the ring architecture occurs. The redundancy manager shuts down this connection once the cause of the interruption has been rectified. Hence, although the ring is physically intact, it is interrupted from a communication point of view.

Reference potential Potential from which the voltage of the electrical circuits are observed and / or measured.

Remote Network Monitoring

Please refer to →RMON

Request for Comments Please refer to →RFC xxx

Resource Reservation Setup Protocol

Please refer to →RSVP

Return loss Describes the reduction of amplitude of the signal during transmission in a →cable. With increasing frequency and / or cable length, the attenuation increases, which means the level of the signal deteriorates.

Reverse Address Resolution Protocol

Please refer to →RARP

RFC xxx Request for Comments Request for CommentsAn abbreviation prominent in Internet circles. It is very closely associated with the publication of Internet standards. RFCs are numbered in the sequence they are adopted

RIP Routing Information Protocol A protocol for cyclic exchange of routing tables per →broadcast between →routers within autonomous networks. RIP is one of the oldest, simplest and most widespread routing protocols there is. The more complex →OSPF is considered its successor.

141Glossary

Ripple, permissible Corresponds to the ratio between the peak-to-peak amplitude values of the AC component and the upper limit of the signal value.

RJ45 Denotes the usual connection technique with →twisted-pair cables in office environments. Often known as a western connector.

RMON Remote Network Monitoring A →network management protocol. RMON defines nine classes of collectable data on the lower layers of the →ISO/OSI Reference Model. Data is then subsequently transmitted, for example, via the →Simple Network Mana-gement Protocol (SNMP) to a →network management station.

RMON 2 Remote Network Monitoring 2 A →network management protocol. RMON 2 is an extension of →RMON extending into the higher levels of the →ISO/OSI Reference Model.

Router A device operating on layer 3 of the →ISO/OSI Reference Model connecting different network segments with one another or separating them for purposes of network security or to limit →broadcasts in sub-networks. A router only transfers data packets to other segments sent to its own →MAC address. Subsequently, the router forwards the data packets based on routing tables. That means that transmitting stations must know that the intended recipient is not in the same network. The transmitting station extracts this information from the →IP address of the recipient. Routing tables are either pre-defined or are ‘learnt’ by the router by means or →routing protocols.

Routing A function on layers 3 and 2 of the →ISO/OSI Reference Model. A distinction is drawn between →dynamic an →static routing. →Dynamic routing provides optimum support for the transmission of data, whereas →static routing supports the transmission of data, speech and video on an equal basis.

Routing, dynamic Utilising dynamic routing, →routers calculate the control and parameters for choosing the path through the network. This information is stored in routing tables and exchanged between the →routers via →routing protocols. Through this process, the optimum path is automatically adapted to suit the current topology and network load. Each telegram is routed individually. Thus, telegrams can be received by the recipient in a different order to which the transmitting station sends them.

142

Routing, static With static routing, the paths used for transmitting data between the transmitting and receiving stations are set, and a certain bandwidth reserved for each connection. Thus, data packets transferred between two terminal devices always take the same route. That means there is no possibility of automatically reacting to changes in the →topology or connection overloads. With this process, the →routers need not support any →routing protocols, because all changes to the network structure have to be entered manually in the →routers.

Routing Information Protocol

Please refer to →RIP

Routing protocol Term for protocols utilised by →routers for →dynamic routing in order to exchange information with one another via connected networks. This information is stored in routing tables in the →routers.

RS 232 C Recommended Standard 232 C A widely used serial interface for transferring data with speeds of up to 20 Kbit/s over distances up to 15 m. This interface was standardised by the →EIA as Standard No. 232 in Version C in 1969. Often also known as RS 232.

RS 422 Recommended Standard 422 A serial interface for transmitting data in Full duplex mode. This serial interface was standardised in the 70s by the →EIA as Standard No. 422.

RS 485 Recommended Standard 485 A serial interface for transmitting data that allows a bus structure with several stations. This serial interface was standardised in the 70s by the →EIA as Standard No. 485.

RSTP Rapid Spanning Tree Protocol This protocol prevent that data packets circle between →switches for an endless time. RSTP is defined in →IEEE 802.1 D (issue 2004). Please refer also to →Spanning-Tree

RTP Realtime Protocol A protocol that supports real-time applications. It supports transmission of additional information such as the type of user data transmitted or the time the user data was created.

Rx Abbreviation for receiver. Designation for the connection on a →port at which data is received.

SA Source Address Source address within an →Ethernet packet

Safety extra-low voltage Abbreviation: SELV Low voltage ranging up to 42 V DC. Devices specified as SELV system, are protected against direct or indirect touch; thus ensuring that no dangerous currents flow through the body even when simultaneous contact is made with both poles.

143Glossary

SAP Service Access Point Term for the interface between two layers of the →ISO/OSI Reference Model through which a higher layer can utilise the services of the layer below.

SC Straight Connector A widely known connector for →fibre-optic cables. Please refer to →DSC

SDH Synchronous Digital Hierarchy A European standard defining several standards covering →transmission speeds and forms or transmissions for optical fibres (→fibre-optic cables).

Segmentation Segmentation restricts →collision domains enabling improved performances in →Ethernet networks. Segmentation can, for example, be achieved by utilising →switches. Please refer to →network segmentation

SELV Safety Extra Low Voltage Please refer to →safety extra-low voltage

Service Access Point Please refer to →SAP

SFD Start Frame Delimiter Part of an →Ethernet packet.

Shared network Term used for an →Ethernet network in which all stations share the available bandwidth. Device access to the trans-mission medium in these networks is regulated by the →CSMA/CD mechanism

Shielded Twisted Pair Symmetrical Category 5, →twisted-pair cable consisting of pairs of twisted and shielded wires with an overall shielding either made of aluminium foil or copper braiding to reduce interference from noise or radiation. Impedance is 100 �.

Signal propagation time The time required for a data packet to transmit through a network.

Single-mode fibre A single-mode fibre is a →fibre optic cable distinguished by an extremely low core diameter (max. 10 µm). Because of this, the light can only disperse above the cutoff wave-length along one path – one mode. The distance to be bridged along a single-mode fibre depends on several factors: the rated data of the fibres, the link budget as well as the attenuation through connectors, splices and other components.Signal bandwidths:• →Ethernet = 10 MHz,• →Fast Ethernet = 125 MHz• →Gigabit Ethernet = 1.25 GHz

Skilled person (electrician) (to DIN EN 50 110-1)

A specialist, who with suitable training, knowledge and experience can recognise and avoid danger resulting from working with electricity (IEV 826-09-01, modified)

144

SNMP Simple Network Management Protocol →IETF standardised protocol for →network management of communication between →switches and the manage-ment station. Please refer also to →RFC 1157 / →RFC 1156 and in the web: www.ietf.org

Source Address Please refer to →SA

Spanning tree Term used for a protocol used in →Ethernet networks to determine the path. It is specified as the standard →IEEE 802.1 D. In this process, the entire network is considered to be a tree in which the terminal devices are represented by the leaves and the →switches by the branches or the roots. By disconnecting individual connections or →ports, the spanning tree algorithm prevents data packets from flying around within a →LAN containing several possible paths. In addition, it determines the optimum path when several alternatives are available. Should a path become disabled due to interference or interruption, the spanning tree protocol searches for an alternative path. Reconfiguration of this type of network can take between 30 to 90 seconds.

S/STP Screened Shielded Twisted Pair The individual twisted wire pairs of a →twisted-pair cable are wrapped with a foil shield in this type of cable construction. Both individual shielded wire pairs are enclosed in a common copper braid.

ST A widely used →connector with bayonet lock for →fibre-optic cables. Also known as a →BFOC connector. The only standardised connector for →Ethernet (10 Mbit/s) (ST is a registered trademark of AT&T).

Star coupler Please refer to →hub

Start Frame Delimiter Please refer to →SFD

Store and Forward Operating mode in which the →switch temporarily stores the respective data packet, checks it for errors and, if it is error free, forwards it to its destination →port.

STP Please refer to →Shielded Twisted Pair

Straight Connector Please refer to →SC

Structured cabling Application-independent cabling of buildings for technical information purposes in accordance with EN 50173 ‘Generic cabling systems’. This standard divides locations in:• Primary areas (connecting buildings at a location)• Secondary areas (connecting different floors of a

building)• Tertiary areas (technical connections for terminal

equipment). For these areas, the EN 50173 standard contains recommendations for suitable cabling systems that are both flexible and generic as well as being equipped to fulfil future communication requirements.

145Glossary

Subnet mask Network mask The network mask marks all of the bits contained in an IP address that identify the network and sub-networks. It is a method for dividing several IP networks into a string of subgroups or sub-networks. The network mask is a bit pattern that must fit the →IP addresses in the network. The standard subnet mask is 255.255.255.0. In this case, 254 different IP addresses, from x.x.x.1 to x.x.x.254, can occur in a sub-network. Please refer to →IP address

Switch A device operating on layer 2 of the →ISO/OSI Reference Model. In contrast to →hubs, switches analyse the incoming data packets and forward these only to the →port to which the recipient is registered. Excluded from these targeted switching operations are →multicasts and →broadcasts, which are transmitted to all →ports. Data packets can be transmitted to several →ports simultaneously and in →Full duplex mode. In doing so, switches are able to optimise the available →LAN bandwidth. In the mean time, there are so-called layer-3 and layer-4 switches that also have some of the functions of these layers implemented in them.

Switch, blocking →Switch that can process only a limited number of connections simultaneously when operating full data transmission rates.

Switch, managed →Switch with management functions; controls data traffic in accordance with parameters / rules

Switch, non-blocking →Switch that can process all connections without delay when operating full data transmission rates

Switch, unmanaged →Switch without →management functions; switches the entire data traffic based on the →address/port assignment table

Switch matrix Matrix covering all connections between all →ports of a switch.

Switched network Term for a →switch-based →Ethernet network

Synchronous Digital Hierarchy

Please refer to →SDH

Tag Optional field in the →Ethernet →frame that contains information relating to priority of the user data and membership of a →VLAN; inserted after the source data.

TCP Transmission Control Protocol TCP is a connection-oriented protocol on layer 4 of the →ISO/OSI Reference Model. Mostly utilized for transferring large amounts of data, this protocol is responsible for error-free transmission of data.

TCP/IP Transmission Control Protocol / Internet Protocol TCP/IP is the standard Internet protocol that is not only composed of →TCP and →IP, but contains a range of protocols.

Terminating resistor A resistor used for line termination of triaxial cables used for →Industrial Ethernet.

146

TFTP Trivial File Transfer Protocol An →ISO/OSI Reference Model layer-5 protocol that uses →UDP for fast and uncomplicated transmissions of files. TFTP is a considerably leaner and less complex than →FTP.

Thick Wire Please refer to →10Base-5

Thin Wire Please refer to →10Base-2

Time To Live Please refer to →TTL

Topology Layout structure of a network

TOS Type Of Service A field in the Internet protocol that oversees prioritising of data.

TP Please refer to →twisted-pair

Transceiver • General term for a component used for transmitting and receiving.

• Term for media converters within the Rail family of products.

• Components that convert data signals from an →AUI interface to another medium.

There are two plug-on transceivers for →fibre-optic cables, →twisted-pair and coaxial cables. The latter are supplied with power from the connected terminal device via the 15-pole →AUI interface.

Transmission Control Protocol

Pleaser refer to →TCP

Transmission Control Protocol / Internet Protocol

Pleaser refer to →TCP/IP

Transmission path Complete transmission path connecting two user-specific facilities with each other. Device connection cables are a part of the transmission path.

Transmission rate The speed of data transmission also known as bandwidth; with →Ethernet, the following transmission rates are possible: • 10 Mbit/s (→Ethernet)• 100 Mbit/s (→Fast Ethernet)• 1000 Mbit/s (→Gigabit Ethernet)• 10 000 Mbit/s (10 Gigabit-Ethernet)

Transport Control Protocol Pleaser refer to →TCP

Trap Term for the message concerning spontaneous events, such as error messages to a →network management station.

Triaxial cable →10Base-5 compliant data cable that, with a solid aluminium shield and outer sheath, has been adapted for use in industry.

Trivial File Transfer Protocol

Please refer to →TFTP

Trunking Please refer to →link aggregation

147Glossary

TTL Time To Live A field in the header of the Internet protocol detailing for how long the packet is valid.

Tunnelling Term used for packaging of data in the data packet of a different protocol operating on the same layer of the →ISO/OSI Reference Model. Encapsulation is another name give to this process.

Twisted-pair Denotes point-to-point connection method using a data cable with →twisted-pair cables (shielded or unshielded) in an →Ethernet network. The opposing effects of →EMC interferences in the individual wire loops of the twisted-pair cables cancel each other out.

Tx Abbreviation for transmitter. Term for the connection on a →port from which the data is transmitted.

Type Of Service Please refer to →TOS

UDP User Datagramm Protocol Operating on layer 4 of the →ISO/OSI Reference Model, UDP is a connectionless protocol that is particularly suitable for fast cyclic data traffic. Transmissions using UDP protocols are generally faster than with →TCP, however errors are not fixed.

UL Underwriters Laboratories American institute for quality assurance of technical products.

Unicast Term for transmitting a message to a specified recipient.

Unmanaged Please refer to →switch, unmanaged

Unshielded Twisted-pair Symmetrical →twisted-pair cable with unshielded wires twisted in pairs without overall shielding

UTP Please refer to →Unshielded Twisted Pair

VDE Verband der Elektrotechnik, Elektronik und Informationstechnik German Association for Electrical, Electronic and Information Technologies

Virtual Redundant Router Protocol

Pleaser refer to →VRRP

VLAN Virtual LAN A →switch-based →virtual LAN tasked with restricting →broadcasts to the network areas in which the →broad-cast is of use. Also used to separate networks for security purposes.

VRRP Virtual Redundant Router Protocol A protocol for controlling redundant →routers.

WAN Wide Area Network Term used for private or public networks that often connect several →LANs with each other.

Weighted Fair Queuing Please refer to →WFQ

148

WEP Wired Equivalent Privacy A coding mechanism based on a key length of 40/64 bits and 104/128 bits. WEP is defined in →IEEE 802.11.

WFQ Weighted Fair Queuing A procedure according to which the queues in a →switch are processed, if the data is prioritised. Due to the bandwidths assigned to the queues, this procedure guarantees that all queues are processed.

Wide Area Network Please refer to →WAN

Wire Speed Term used for forwarding data packets at the speed allowed by the physical properties of the wire.

Wired Equivalent Privacy Please refer to →WEP

Wireless LAN Pleaser refer to →WLAN

WLAN Wireless Local Area Network A group of stations connected to one another without wires (wireless →LAN).

Xmodem Protocol for transmitting data between stations. The data is divided up into 128-byte blocks. Errors in the data are corrected.

Yellow Cable Please refer to →10Base-5

Zero potential The zero potential is the sum of all connected, inactive components of equipment that, even in the event of a fault, cannot take on a dangerous shock hazard voltage.

149Glossary

150

151Degrees of Protection

Degrees of Protection

HARTING can draw on many years of extensive experience gained in achieving high degrees of protection in industrial environments (IP 65 and greater); all of which has flowed into the development of its family of devices.

These devices achieve their degree of protection as a result of the corresponding housings and covers or by the interlocking of their connections. Depending on the degree of protection, the devices are protected from external mechanical influences (impacts, foreign objects, dust, and accidental touch contact) as well as against ingress of moisture (water, cleaning agents, oils and other fluids).

The degree of protection provided by a device is defined in the standards EN 60 529 and IEC 60 529, which also contain a classification of the different degrees of protection.

In accordance with the above-mentioned standards, the degrees of protection are indicated as follows:

Code letters (International Protection)

IP

First Index Figure (Protection against

solid foreign objects)

6

Second Index Figure (Protection against water)

5

The following pages contain an overview of the individual codes and their meaning.

152

Index figure

Scope of protection against solid foreign objects and mechanical contacts

Firs

t Ind

ex F

igur

e

0 No protection • No protection against accidental contact

• No protection against solid foreign objects

1 Protection against large foreign objects

• Protection against contact with any large area by hand

• Protection against large solid foreign objects with Ø > 50 mm

2 Protection against medium sized foreign objects

• Protection against contact with the fingers

• Protection against solid foreign onjects with Ø > 12 mm

3 Protection against small solid foreign objects

• Protection against tools, wires or similar objects with Ø > 2,5 mm

• Protection against small solid foreign objects with Ø > 2,5 mm

4 Protection against grain-shaped foreign objects

as 3 however Ø > 1 mm

5 Protection against injurious deposits of dust

• Full protection against contact• Protection against interior

injurious dust deposits

6 Protection against ingress of dusts

• Total protection against contact• Protection against penetration

of dust

153Degrees of Protection

Index figure

Scope of protection against water and other fluidsSe

cond

Inde

x Fi

gure

0 No protection against water

No protection against water

1 Drip-proof (vertical) Protection against vertical water drips

2 Drip-proof (angular) Protection against water drips (up to a 15° angle)

3 Spray-proof Protection against diagonal water drips (up to 60° angle)

4 Splash-proof Protection against splashed water from all directions

5 Hose-proof Protection against water (out of a nozzle) from all directions

6 Protection against flooding

Protection against temporary flooding

7 Protection against immersion

Protection against temporary immersion

8 Water-tight Protection against water pressure

154

155List of figures

List of figures

Figure 1-1 Cable installation based on conventional wiring .........13

Figure 1-2 Cable installation based on a fieldbus ........................14

Figure 1-3 Overview of transmission rates for various classic fieldbus systems and Industrial Ethernet ....................16

Figure 1-4 The automation pyramid .............................................17

Figure 1-5 ISO/OSI Reference Model ..........................................20

Figure 1-6 Example of message transmission utilising a fieldbus in accordance with the ISO/OSI Reference Model .....22

Figure 1-7 Classifying the fieldbus systems .................................23

Figure 2-1 Ethernet – The idea ....................................................25

Figure 2-2 Development of Ethernet to date ................................26

Figure 2-3 Ethernet and the ISO/OSI Reference Model ...............27

Figure 2-4 Structure of a MAC address ........................................29

Figure 2-5 Standard Ethernet Frame ...........................................30

Figure 2-6 Path taken by an Ethernet telegram ...........................31

Figure 2-7 Path taken by broadcast telegrams ............................31

Figure 2-8 Path taken by multicast telegrams (group 1) ..............32

Figure 2-9 Path taken by multicast telegrams (group 2) ..............32

Figure 2-10 Sequence of a data transmission with CSMA/CD .......33

Figure 2-11 Schematic portrayal of the CSMA/CD method ............34

Figure 2-12 Carrier Extension for a short Gigabit Ethernet frame (data field < 493 bytes) ...............................................38

Figure 2-13 Conventional system extension operating different fieldbus systems .........................................................41

Figure 2-14 System extension based on Ethernet / Industrial Ethernet ......................................................................42

Figure 2-15 Harsh industrial conditions – operating in a steelworks ....................................................................................44

Figure 2-16 Fast data transmission to control industrial robots manufacturing automobiles .........................................44

Figure 2-17 Wind turbines – high demands on EMC and mechanical stability .....................................................45

156

Figure 3-1 Structured cabling in the office area in accordance with EN 50 173-1 ........................................................53

Figure 3-2 PROFINET-compliant structured industrial network in accordance with EN 50 173-1 .................................54

Figure 3-3 Star topology with an Ethernet switch .........................55

Figure 3-4 Tree topology with Ethernet switches .........................56

Figure 3-5 Line topology with Ethernet switches ..........................56

Figure 3-6 Ethernet components in the ISO/OSI Reference model ..........................................................................57

Figure 3-7 Comparison of Ethernet and PROFIBUS structures based on theISO/OSI Reference Model .....................58

Figure 3-8 Function principle of a gateway (example: Ethernet and PROFIBUS) .........................................................58

Figure 3-9 Gateways as a link between Industrial Ethernet and PROFIBUS (Example) ................................................59

Figure 3-10 Communication between Ethernet networks with routers .........................................................................59

Figure 3-11 Function principle of an Ethernet switch .....................61

Figure 3-12 Operating mode ‘Store and Forward’ ..........................63

Figure 3-13 Industrial utilisation of Ethernet switches sealed to IP 20 ............................................................................65

Figure 3-14 Industrial utilisation of Ethernet switches sealed to IP 65 / IP 67 ................................................................66

Figure 3-15 Construction of the ESC TP05U HARTING RJ Industrial® .............................................................69

Figure 3-16 Block diagram of Ethernet switch ESC 67-10 TP05U ....................................................................................70

Figure 3-17 Options for utilising ‘In-between’ Ethernet switches ....71

Figure 3-18 Example of a structure based on ‘In-between’ Ethernet switch and Ethernet switch for direct mounting .....................................................................72

Figure 3-19 Construction of the ESC 67-30 TP05U HARTING RJ Industrial® .............................................................73

Figure 3-20 Block diagram of ‘In-between’ Ethernet switch ESC 67-30 TP05U ......................................................73

Figure 3-21 Difference between an Ethernet hub and an Ethernet switch ..........................................................................74

Figure 3-22 Function principle of an Ethernet hub .........................75

157List of figures

Figure 3-23 Industrial utilisation of Ethernet hubs sealed to IP 20 ....................................................................................76

Figure 3-24 Industrial utilisation of Ethernet hubs sealed to IP 65 / IP 67 ................................................................77

Figure 3-25 Construction of EHB 67-10 TP05 M12 D-coding ........80

Figure 3-26 Block diagram of Ethernet hub EHB 67-10 TP05 .......80

Figure 3-27 Structured cabling to ISO/IEC 11 801:2002 with Industrial Outlets .........................................................81

Figure 3-28 Industrial Outlet in a production facility at Daimler Chrysler AG, Rastatt (source: HARTING) .....83

Figure 3-29 Construction of INO 67 HARTING RJ Industrial® .......83

Figure 3-30 Cable properties in conjunction with the category used ...................................................................................87

Figure 3-31 Twisted-pair cable with two cable pairs (example: for permanent installation) ..........................................88

Figure 3-32 Maximum transmission length of Ethernet cables ......89

Figure 3-33 Hybrid cable with 2 sets of shielded data lines and 4 copper wires for the power supply ...........................90

Figure 3-34 Possible connectors for Industrial Ethernet from HARTING ....................................................................93

Figure 3-35 Connectors for Industrial Ethernet in IP 20 ................94

Figure 3-36 HARTING RJ Industrial® connectors to IP 20 in use at the Stadler Rail Group, Switzerland (source: HARTING) .....................................................94

Figure 3-37 HARTING RJ Industrial® IP 67 Data 3A connectors in use on robots (source: HARTING) ..........................97

Figure 3-38 Hybrid connector .........................................................98

Figure 3-39 Contact assignment for 1:1 cable (example: RJ45, 2-pair) ..........................................................................98

Figure 3-40 Contact assignment for cross-over cable (example: RJ45, 2-pair) ...............................................................99

Figure 3-41 Contact assignment for circular connector M12 D-coding (female / male) .....................................99

Figure 3-42 Contact assignment (pairs) RJ45, 4-pair ..................100

Figure 3-43 Contact assignment (pairs) RJ45, 4-pair for Gigabit Ethernet ....................................................................101

158

Figure 3-44 Contact assignment for 1:1 cable and Gigabit Ethernet ..................................................................................102

Figure 3-45 Contact assignment for cross-over cable and Gigabit Ethernet ....................................................................102

159List of tables

List of tables

Table 2-1 Overview of address types ..........................................29

Table 2-2 Standard Ethernet frame .............................................30

Table 2-3 Influence of the transmission rate on the collision window and maximum transmission path ...................34

Table 2-4 Comparison between Ethernet and Fast Ethernet ......35

Table 2-5 Comparison of Gigabit Ethernet with Ethernet and Fast Ethernet ..............................................................37

Table 2-6 Different requirements for office and industrial environments ..............................................................46

Table 2-7 Different requirements for network components in office and industrial environments ..............................47

Table 2-8 Overview of the current Ethernet protocols .................50

Table 3-1 Comparison between the operating modes ‘Store and Forward’ and ‘Cut Through’ ..................................64

Table 3-2 Comparison between Ethernet switch sealed to IP 20 and Ethernet switch sealed to IP 65 / IP 67 .......67

Table 3-3 Comparison between Ethernet hub sealed to IP 20 and Ethernet switch sealed to IP 65 / IP 67 ................78

Table 3-4 Various solutions available for Ethernet cabling .........84

Table 3-5 Environmental influences in various fields of industry ....................................................................................85

Table 3-6 Transmission media for Ethernet protocols ................86

Table 3-7 Overview of cable category assignment .....................87

Table 3-8 Overview of cable class assignment for transmission channels ......................................................................87

Table 3-9 Maximum cabling lengths for Ethernet / Fast Ethernet according to PROFINET specifications .......................89

Table 3-10 Special fibre-optic cables for Gigabit Ethernet ............91

Table 3-11 Twisted-pair cables for Gigabit Ethernet .....................91

Table 3-12 Overview of fibre-optic cable for 10 Gigabit Ethernet ....................................................................................91

Table 3-13 Power on Ethernet (PoE) performance classes ..........92

Table 3-14 Different connectors for Industrial Ethernet in IP 65 / IP 67 ............................................................................95

Table 3-15 HARTING connectors .................................................96

160

Table 3-16 Contact assignment for 1:1 cable ...............................98

Table 3-17 Contact assignment for cross-over cable ....................99

Table 3-18 Contact assignment for RJ45, 2-pair (colour code) ....99

Table 3-19 Contact assignment, circular connector M12 D-coding (colour code) ......................................100

Table 3-20 Contact assignment, wire pairs RJ45 connector .......100

Table 3-21 Contact assignment RJ45 according to EIA/TIA 568 (colour code) .............................................................101

Table 3-22 Contact assignment for wire pairs, RJ45 connector for Ethernet / Fast Ethernet and Gigabit Ethernet .....102

Table 5-1 Overview of types of components for Industrial Ethernet from HARTING ..........................................105

Table 5-2 Overview of types of Ethernet switches for direct mounting ...................................................................106

Table 5-3 Overview of types of Ethernet switches for mounting on to exterior cabinet panels from HARTING ...........106

Table 5-4 Overview of types of Ethernet hubs to IP 67 from HARTING ..................................................................107

Table 5-5 Overview of types of Industrial Outlets from HARTING ..................................................................107

Table 5-6 Mounting options .......................................................108

Table 5-7 Cable types for Ethernet switches ............................108

Table 5-8 Cable types for Ethernet hubs and outlets ................109

Table 5-9 Examples of cable types ...........................................109

Table 5-10 Connector variants .................................................... 110

161Index

Index

0 ... 91000Base-LX ................................................................................................. 861000Base-SX ................................................................................................ 861000Base-T ................................................................................................... 86100Base-FX .................................................................................................. 86100Base-TX .................................................................................................. 8610Base-FL ..................................................................................................... 8610Base-T ....................................................................................................... 8610 Gigabit Ethernet ....................................................................................... 38

cable ....................................................................................................... 91

Aaccumulated frame telegram ......................................................................... 24address/port assignment table ...................................................................... 60address types ................................................................................................ 29application layer ............................................................................................ 21Auto-crossing ................................................................................................ 61Auto-negotiation ...................................................................................... 35, 61Auto-polarity .................................................................................................. 62Auto-sensing ................................................................................................. 75automation pyramid ....................................................................................... 17availability ...................................................................................................... 47

Bbit transmission layer ..................................................................................... 20block diagram

Ethernet hub ........................................................................................... 80Ethernet switch ....................................................................................... 70In-between Ethernet switch ..................................................................... 73

bridge ............................................................................................................ 60broadcast ................................................................................................. 20, 31bus access, deterministic .............................................................................. 23bus access, random ...................................................................................... 23

Ccable, category .............................................................................................. 87cable, class .................................................................................................... 87cable, hybrid .................................................................................................. 90cable, properties ............................................................................................ 87cable, twisted-pair ......................................................................................... 88cabling, structured ................................................................................... 53, 81

162

carrier extension ............................................................................................ 37Carrier Sense ................................................................................................ 33Carrier Sense Multiple Access ...................................................................... 23category ......................................................................................................... 86cell level ......................................................................................................... 18CIP ................................................................................................................. 50class .............................................................................................................. 87collision .......................................................................................................... 33collision, freedom from ............................................................................ 47, 61Collision Detection ......................................................................................... 33collision domain ....................................................................................... 33, 61collision window ............................................................................................. 34colour code .................................................................................... 99, 100, 101communication layer ..................................................................................... 21conditions, environmental .............................................................................. 85connector ....................................................................................................... 93

IP 20 ........................................................................................................ 94IP 65 / IP 67 ............................................................................................ 94overview in IP 65 / IP 67 ......................................................................... 95

connector, hybrid ........................................................................................... 97contact assignment ....................................................................................... 98

1:1 cable ................................................................................................. 98cross-over cable ...................................................................................... 98Gigabit Ethernet .................................................................................... 101M12 D-coding .......................................................................................... 99RJ45, 2-pair ............................................................................................ 99RJ45, 4-pair .......................................................................................... 100

Control and Information Protocol ................................................................... 50control level ................................................................................................... 18copper cable .................................................................................................. 88cross-over function ........................................................................................ 79CSMA ............................................................................................................ 23CSMA/CD ................................................................................................ 27, 33Cut Through ................................................................................................... 63

Ddata link layer ................................................................................................ 20data port ............................................................................................ 69, 73, 80destination address ....................................................................................... 30dual speed hub .............................................................................................. 74

EEndpoint PSE, operating mode B .................................................................. 92EtherCat ........................................................................................................ 52

163Index

Ethernet, address .......................................................................................... 28Ethernet, classic ...................................................................................... 25, 26Ethernet, development .................................................................................. 26Ethernet, frame .............................................................................................. 30Ethernet, protocol variants ............................................................................ 50EtherNet/IP .................................................................................................... 50Ethernet cabling

solutions .................................................................................................. 84standardisation ........................................................................................ 84

ETHERNET PowerLink ................................................................................. 51

FFast Ethernet ................................................................................................. 35FDX ............................................................................................................... 36fieldbus systems, classification ..................................................................... 22field level ....................................................................................................... 17flow control .................................................................................................... 36frame bursting ............................................................................................... 38Full duplex ............................................................................................... 36, 62

Ggateway ......................................................................................................... 58Gigabit Ethernet ...................................................................................... 36, 90

copper cables .......................................................................................... 91fibre optics ............................................................................................... 90

HHalf duplex .................................................................................................... 62HSE ............................................................................................................... 52hub ................................................................................................................ 74hub, function principle ................................................................................... 75hybrid cable ................................................................................................... 90

IIAONA ........................................................................................................... 49IEEE .............................................................................................................. 25impedance ..................................................................................................... 88In-between Ethernet switch ........................................................................... 70Industrial Outlet ............................................................................................. 81instance ......................................................................................................... 20ISO/OSI Reference Model ................................................................. 19, 21, 26

164

Jjam signal ................................................................................................ 31, 33JetSync .......................................................................................................... 52

K

Llayer model .................................................................................................... 19lifetime, operational ....................................................................................... 47locking lever .................................................................................................. 69

MMAC address ................................................................................................. 28management function .................................................................................... 62management level ......................................................................................... 19master............................................................................................................ 23mating face .................................................................................................... 93Medium Access Control ................................................................................. 28Midspan PSE, operating mode B .................................................................. 92Modbus/TCP .................................................................................................. 52Modified Cut Through .................................................................................... 63multicast .................................................................................................. 20, 32

Nnetwork, structured ........................................................................................ 54network component, active ............................................................................ 57network component, passive ......................................................................... 57network layer ................................................................................................. 21network topology ........................................................................................... 55

Ooperating mode

Cut Through ............................................................................................ 63Modified Cut Through .............................................................................. 63Store and Forward .................................................................................. 63

OSI Model ..................................................................................................... 19

Ppatch cable .................................................................................................... 88physical layer ................................................................................................. 20PoE ................................................................................................................ 91

165Index

Power on Ethernet ......................................................................................... 91Endpoint PSE, operating mode B ........................................................... 92Midspan PSE, operating mode B ............................................................ 92operating mode A .................................................................................... 92operating mode B .................................................................................... 92performance classes ............................................................................... 92

preamble ....................................................................................................... 30presentation layer .......................................................................................... 21process control level ...................................................................................... 19process level ................................................................................................. 18PROFINET .................................................................................................... 51protection cover ............................................................................................. 69protocol .......................................................................................................... 19

Q

Rreal-time................................................................................................... 48, 61real-time communication capability ............................................................... 48repeater ......................................................................................................... 74requirements, environmental ......................................................................... 46requirements, general ................................................................................... 45requirements, installation .............................................................................. 46response time ................................................................................................ 47router ............................................................................................................. 59

Ssafeethernet .................................................................................................. 52SERCOS-III ................................................................................................... 52session layer ................................................................................................. 21signal propagation time, maximum ................................................................ 34slave .............................................................................................................. 24SNMP Management ...................................................................................... 62standards ..................................................................................................... 113starting frame delimiter .................................................................................. 30status indication ................................................................................. 69, 73, 80Store and Forward ......................................................................................... 63switch............................................................................................................. 60switch, blocking ............................................................................................. 62switch, function principle ............................................................................... 61switch, managed ........................................................................................... 62switch, non-blocking ...................................................................................... 62switch, unmanaged ....................................................................................... 62

166

Switched Ethernet ................................................................................... 39, 61switch matrix .................................................................................................. 62system, deterministic ..................................................................................... 39system extension, based on Ethernet ........................................................... 42system extension, conventional .................................................................... 41system level ................................................................................................... 18

TTCP ............................................................................................................... 28telegram

broadcast .......................................................................................... 20, 31multicast ............................................................................................ 20, 32unicast ..................................................................................................... 20

tests, EMC ..................................................................................................... 47tests, safety ................................................................................................... 47Time Division Multiplex .................................................................................. 22token .............................................................................................................. 23Token Passing ............................................................................................... 23topology

line .......................................................................................................... 56ring .......................................................................................................... 56star .......................................................................................................... 55tree .......................................................................................................... 55

Transmission Control Protocol ...................................................................... 28transmission length, max. .............................................................................. 89transmission media ....................................................................................... 86

1000Base-LX .......................................................................................... 861000Base-SX .......................................................................................... 861000Base-T ............................................................................................. 86100Base-FX ............................................................................................ 86100Base-TX ............................................................................................ 8610Base-FL ............................................................................................... 8610Base-T ................................................................................................. 86

transmission performance ............................................................................. 46transport layer ............................................................................................... 21trunking .......................................................................................................... 36

UUDP ............................................................................................................... 28unicast ........................................................................................................... 20user data ....................................................................................................... 30User Datagram Protocol ................................................................................ 28

167Index

V

W

X

Y

Z

168

Documents

Industrial Ethernet - from the Office to the Machineschusterusa.com/.../harting_industrial_ethernet_handbook.pdf · 2013. 8. 27. · HARTING The best connections worldwide – because