Profibus DP_Technical Presentation En

8/12/2019 Profibus DP_Technical Presentation En

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Slide 1 / 32BU Automation Product Support - Training

PhB - Profibus DP_Technical Description_en - 04 / 2007

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Application layer

Link layer

Physical layer

What is Profibus DP

Profibus DP description

To summarize


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Application layer

Link layer

Physical layer

What is Profibus DP

What is Profibus DP

To summarize


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Profibus = PROcess FIeld BUS

Initialized in 1987 by the German Ministry for Research and TechnologicalDevelopment.

Now managedby an association of PROFIBUS :

- Manufacturers, Users and research institutions

- More than 1100 menbers worldwide (Profibus International)

Conforms to standard EN 50 170

History

Profibus International Organization :

www.profibus.com


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Profibus versions

ProfiNet : PROFIBUS on Ethernet/TCP-IP

Sensor

level

Machine

level

Wo

rkshop

lev

el

Manag

ement

level


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Field buslevel to connect Distributed Peripherals

I/O modules

Speed drive unit

Valves

Operator terminal,

Profibus DP

Data exchange transmission types Cyclicallydata exchange : Process Data

Aperiodicalydata exchange : Parameters, Alarms and Diagnostic


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APPLICATION

LAYER7

PRESENTATION

LAYER6

1

SESSION

LAYER5

TRANSPORT

LAYER4

Profibus DP OSI model

NETWORK

LAYER3

2

PHYSICAL

LAYER

LINK

LAYER

DP functions Data exchanges, Diagnostic,

Application ProfilesRemote I/O, Speed drive,

encoder,

RS485 or Fiber optic

Multi-Masters and Master/Slaves


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Application layer

Link layer

Physical layer

What is Profibus DP

Physical layer

To summarize


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Transmission technologies

The technologies

RS 485 (2 wires) : Universal applications

Fiber optical (multimode/singlemode) : EMC immunity and longer distances

IEC 61 158-2 (4 wires) : Process applications

RS 485 Intrinsically Safe (4 wires) : Process application in explosive areas

RS485 is the transmission technology most

frequently used by Profibus-DP.


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Profibus nodes addressing

Each node must have its own & unique address

Address range : 1 to 125

Address 126 : reserved for address assignment via the bus

Address 127 : reserved for broadcast and multicast communication

Address 1

PLC

Remote I/ODrive Remote I/O

Address 4Address 8

Address 3


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Line Topology for RS485

Bit-rate : 9,6 Kbits/s to 12 Mbits/s

125 devices max. in a fieldbus with 32 devices max. per segment

The length of a segment depends on the bit-rate

Each segment forms a line with a termination resistor at the

beginning and at the end

Device 1

Device 3

Device 4

32 max.

Bus termination

Bus terminationDevice 2

.


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Cable specification

Cable types are available for

Fixed Installation

Underground Installation

Trailing Chain

Cable ASchneider reference :

TSX PBS CA100 (100m) or TSX PBS CA400 (400m)

Parameter Cable Type A (fixed installation)

Cable design two-wire, twisted pair

Loop impedance < 110 W per km

Impedance (nominal) 135 165 W @ f = 3 20 Mhz

Wire diameter > 0.64 mm

Wire cross section > 0.34 mm

Operating capacity 30 pF / m


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Segment length

Bit rate 9.6 Kb/s 187.5 Kb/s 500 Kb/s 1,5 Mb/s 3 Mb/s

19.2 Kb/s 6 Mb/s

93.75 Kb/s 12 Mb/s

Length (cable type A) 1200 m 1000 m 400 m 200 m 100 m

The length of a network can be enlarged by the use of repeaters

The max. number of repeaters between a master and a node is

depending from the type of the repeater and is can vary between

3 and 9.


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Repeaters usingNote :Repeaters do not have

bus addresses but do count as

device (bus load) in a segment!

A segment consists of up to 32 bus loads

The beginning and the end of a bus/segment must be terminated

(termination resistors)

The termination resistors must always be supplied with voltage

Device 1

Device 3

Repeater

Bus termination

Bus terminationDevice 2

Device 31

Device 32

Repeater

Device 60Bus termination

Device 61

The repeater(s) allows to increase the length

of the bus or/and the devices number


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Bus termination

VP* (6)

B (3)

A (8)

DGnd* (5)

VP* (6)

B (3)

A (8)

DGnd* (5)

390 W

220 W

390 W

390 W

220 W

390 W

A (8) B (3)

Device 2

A (8) B (3)

Station 3

Data line A

Data line B

Device 3

* Each device must provide the power supply for the termination resistor (VP=5 VDC)


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D-SUB connector

9 pin DSUB male connectors recommended for IP20

The socket (female) is on the device

Schneider offer :-490 NAD 911 03 : with termination resistor

-490 NAD 911 04 : without termination resistor

-490 NAD 911 05 : with selection of termination resistorInput Bus Output Bus

Station 3

Pin Signal Description

1 Shield Shield/Protective earth

2 M24 ground for 24V output voltage

3 RxD/TxD-P * Transmit-/Receive data positive (B line), color = red

4 CNTR-P Repeater control signal positive

5 DGND * Data Ground

6 VP * Supply voltage for the termination resistors (5V)

7 P24 Output voltage positive 24V8 RxD/TxD-N * Transmit-/Receive data negative (B line), color = green

9 CNTR-N Repeater control signal negative

* Every device must provide the mandatory signals


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Application layer

Link layer

Physical layer

What is Profibus DP

Link layer

To summarize


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Hybrid access method

PROFIBUS uses a hybridaccess method

Active stations communication is based on the token ring concept.

Passive stations (slaves) uses the master-slave concept.

Active stations = master devices

Passive stations = slaves devices


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Hybrid access method

It is a special telegram master which must be passed around thelogical token ring once to all masters within a (configurable) maximumtoken rotation time.

Token ring

It ensures that the bus access right is assigned to each master within a

precisely defined timeframe.

Master Slave conceptIt permits the master which currently owns the token to access the

assigned slaves (passive devices) and to other masters.

The transmit message send to the slaves and it answer is called PPO (Parameter Process Object).

Note :The Profibus DP module for Premium PLC doesnt support the muti-Master mode


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Frame security mechanisms

Data frame structure example

Start

DelimiterLength

Destination

address.

User Data

(max. 244 bytes)

Frame check

sequence

End

delimiter

Security mechanisms

-Start delimiter and End delimiter

-Parity bit

-Slip-free synchronisation

-Frame Sequence Check (CRC)

-Distance hamming = 4

Note :Profibus DP device can transfert up 244 bytes of input and output data.


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Application layer

Link layer

Physical layer

What is Profibus DP

Application layer

To summarize


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Communication profiles

DP Master class 1 (DPM1)

Central devices which exchanges I/O data with remote field devices

cyclically. Typical devices are PLCs and PCs

DP Master class 2 (DPM2)

Tools using acyclically communication functions for parameter setting,

diagnostic functions or monitoring. Typical devices are engeneering tolls.

DP Slave

Peripheral device performing cyclical exchanges with "its" active

station.

F i li f h P fib DP


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Functionnality of the Profibus DP

Basic functions : DP-V0

Cyclic Data Exchange between PLC and Slave devices

Diagnostic functions : diagnostic message are transmitted over the bus

and collected by the master

Bus configuration via device electronic file (GSD file)

Extended functions : DP-V1

All functions DP-V0 and,

Acyclic Data Exchange between PC or PLC and Slave devices :

-Parameter assignment,

-Alarm and status handling of intelligent devices

C li l d t h


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When the master sends a request 2 types of exchanges are

included in the cyclical frame

Cyclical exchanges :I/O data

A periodic exchanges :Set up parameters, configuration, diagnostics

Cyclical data exchanges

Aperiodic exchanges are included in the cyclical frames.

When the master receives an answer from the slave, the same

process occurs (2 types of exchanges are included in return)

Cyclical exchanges :I/O data

A periodic exchanges :Parameters monitoring, diagnostics

C li l d t h


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- Periodic exchanges are always used and refreshed (device control & monitoring)

- Aperiodic exchanges are used where necessary

BUT : all words are exchanged cyclically

Cyclical data exchanges

Master sends a cyclical request to slave

PZD

1st word

PKE

PWE

PZD1

PZD2

PZD3

PZDn

last word

aperiodicexchange

periodicexchange

PKW

Output Data

Master receives a cyclical response from slave

1st word

last word

PZD

PKE

PWE

PZD1

PZD2

PZD3

PZDn

aperiodicexchange

periodicexchange

PKW

Input Data

PKW(Parameter - Kennung - Wert): Logical address value

PKE(Parameter - Kennung) : Logical address

PWE(Parameter - Wert): Value of parameter with address in PKE

PZD(Prozedaten) : Process data

A i di h PKW i


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PKE output :

Bits 0 to E : Modbus address of the variableBit F : = 0 Single write or read

= 1 Permanent write or read

R/W output :

= 16#0052 Read

= 16#0057 Write

PWE output :

= If write : Value to be written

PKE input :

Copies of output PKE value

R/W/N input :

= 16#0052 Correct read

= 16#0057 Correct write

= 16#004E Write or read error

PWE input :

If correct read value of the variable

If correct write value of output PWE

If error = 0 : incorrect address

= 1 : write operation refused

Aperiodic exchanges - PKW using

PKW Description

Word 1 PKE output

Word 2 R/W output

Word 3 0

Word 4 PWE output

Output Data

PKW Description

Word 1 PKE input

Word 2 R/W/N input

Word 3 0

Word 4 PWE input

Input Data

Application profile


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Profibus provides some profiles depending of the application to define

an interoperability between similar devices for different vendors.

Application profile

Profile examples

PROFIdrive (Speed drive device)

It specifies the behavior of devices and the access procedure to data for variablespeed drives.

Low-voltage switchgear

It defines data exchange for low-switchgear (motor staters, switch-disconnectors,etc.) on Profibus DP.

Encoders

It describes the interfacing of rotary, angle and linear encoders with single-turn ormulti-turn resolution.

Panel devices (HMI)

It describes the interfacing of simple human machine interface devices (HMI) tohigher-level automation components.

ATV71

TeSys U TeSys T

GSD files


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GSD files

It is readable ASCII text file and contains both general and device-specific specifications supported by the device.

Configuration tool allows :

-Reads the device identification, the adjustable parameters, the data type and

the permitted values for the configuration of the device.

It is provided by the manufacturer for all Profibus devices.

Structure of the GSD file

General specifications

-Contain information on vendor and device names, Hardware & software versions,

supported transmission rates

Master specifications

-Contain all master related parameters, such as: the maximum slaves number that

can be connected, or upload and download options.

Slaves specifications

-Contain all slave related specifications such as: the number and type of I/O channels,

diagnostic texts & information on the available modules in the modular devices case.

Performances typical mono Master system


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The transmission speedmust be fixedin accordancewith :

- The stations capabilities

- The bus length

Performances - typical mono Master system

2

6

10

14

18

5 10 20 30

Bus cycle time [ms]

DP Slaves

Conditions: Each slave has 2 byte input and 2 byte output data.

The minimum slave interval is 200 micro seconds.

The standard default bus parameters are set.

To summarize


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Application layer

Link layer

Physical layer

What is Profibus DP

To summarize

To summarize

To summarize Physical layer


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Topology: Bus with line terminations

Maximum length: Depends on the medium & the data rate

Min.: 100 m for 12 Mbits/s without repeater

Max.: 4800 m for 9.6 kbits/s with 3 repeaters

Data rate: 9,6 Kbits/s to 12 Mbits/s

Max. no. of devices: 32 per segment

125 with repeaters

To summarize - Physical layer

To summarize - Link and Application layer


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Medium access: Token ring between masters

Master slave between master & slaves

Transmission security: Frame Sequence CheckStart & stop delimitersParity bitSlip-free synchronization

Application

level

Data exchanges: Process Data : cyclicallyParameters, diagnostic : aperiodically

Max. useful data size: 244 bytes of PPO for each device

Interoperability: Products certified by Profibus

organization

Interchangeability: Communication & application profiles

To summarize - Link and Application layer

Link

level

Documents

Profibus DP_Technical Presentation En