MEBS6005 Lecture 4 B&W.pdf

7/30/2019 MEBS6005 Lecture 4 B&W.pdf

1/21

1For internal use during lectures only

The Network for

Building AutomationWired Vs Wireless


Networking is the most importantinfrastructure of a modern automatedbuilding.

Networking between computers, betweencontrollers, and between controllers anddevices.

Networks can be WIRED or WIRELESS. Which one is better?


TIA/EIA-568-B defines a hierarchical cable systemarchitecture, in which a main cross-connect (MCC, calledMDF in the past) is connected via a star topology acrossbackbone cabling to intermediate cross-connects (ICC)and horizontal cross-connects (HCC).

Maximum allowable backbone cable distances vary

between 300 m and 3000 m, depending upon the cabletype and use.

Horizontal cross-connects provide a point for theconsolidation of all horizontal cabling, which extends in astar topology to individual work areas such as cubiclesand offices. Under TIA/EIA-568-B, maximum allowable

horizontal cable distance varies between 70 m and 90 mfor twisted-pair cable types, depending upon patch cordlength and gauge.

Fiber optic horizontal cabling is limited to 90 m.4For internal use during lectures only


2/21

5For internal use during lectures only 6For internal use during lectures only

Case Study Home Automation Systemdeveloped by Dr. Brian Tse,City University of Hong Kong


Case Study Home Automation System Linux Server:

Store the web site for users to execute remote controlactions in the Internet

Keep track of the WAN IP address of the system and

send the updated IP address to users IR-Remote-Controlled Electronic Board:

Receive instructions from the Internet through commongateway interface (CGI)

Send IR commands to home appliances such as TV,lighting and fan

Turn on/off the IP camera IP Camera

Allow users to confirm control actions


Case Study Home Automation System

The Whole Setup

Linux

server

IR-Remote-

Controlled

Electronic

Board

Wireless

router

DSL

modem


3/21





IR-Remote-Controlled Electronic Board



Part of the source codes of

the program running inside

Linux server make use of

socket to handle TCP/IP

communication



Linux Servers MAC address

IP Camera

IR-Remote-Controlled

Electronic Board


4/21




Brief Review on

Wired Networks


European Committee deviseda 3-Level Hierarchy:

Level 1 covers sensors and

actuators etc. Level 2 covers field net

between BAS andoutstations

Level 3 is the supervisorylevel



5/21


Attention paid to Physical Layer



Different Networking Topologies


RS - 485

RS485 or EIA (Electronic Industries Association) RS485is a balanced line, half duplex transmission systemallowing transmission distances of up to 1.2 km.


6/21


Connecting the InstrumentsScreened twisted pair cable should be used.

All "A" connections should be connectedtogether using one conductor of the twistedpair cable, all "B" connections should be

connected together using the other conductorin the pair. The cable screen should beconnected to the "Gnd" terminal.


When communicating at high data rates, or over longdistances, single-ended methods are inadequate.

Differential data transmission (balanced differentialsignal) offers superior performance. Differentialsignals can help nullify the effects of ground shifts andinduced noise signals that can appear as commonmode voltages on a network.

RS485 is a truly multi-point communications network,and the standard specifies up to 32 drivers and 32receivers on a single (2-wire) bus.


With the introduction of "automatic" repeaters and high-impedance drivers / receivers this "limitation" can beextended to hundreds (or even thousands) of nodes ona network.

To solve the "data collision" problem often present inmulti-drop networks, hardware units (converters,repeaters, micro-processor controls) remain in a receivemode until they are ready to transmit data.

Single master systems offer a straight forward andsimple means of avoiding "data collisions" in a typical 2-wire, half-duplex, multi-drop system. The master

initiates a communications request to a "slave node" byaddressing that unit.


RS485 is sometimes termed as RS485Multidrop LAN

Officially the RS485 specification allows only 32nodes (devices) on the LAN

These devices are all connected to a single pairof wire. Transmit and receive share the sametwo wires. (i.e. half duplex)

Most RS 485 systems use Master/Slavearchitecture, where each slave unit has aunique address polled by master pc

The maximum data rate is 10 Mbps for 15 mwhile the max. distance is 1200 m at 100 Kbps


7/21


Technical Specifications


ARCnet - 1970s by Datapoint Corporation

Active hubs usually have 8 ports, conditioning andamplifying the signal strength.


ARCNET (Attached Resource Computing Network)is a baseband, token-passing network system thatoffers flexible star and bus topologies at a low price.

Transmission speed was originally 2.5 Mbits/s.

ARCNET has been used for data acquisition,nuclear plant monitoring and control, closed-circuitcameras, building automation, process control, in-flight entertainment system phone switching, point-of-sale systems, stock exchange terminals andmachine control etc. But not popular for LAN.

Support cable lengths up to 600 metres when usingactive hubs.


PROFIBUS (Process Fieldbus) has been standardized allover Europe by CENELEC (European Committee forElectrotechnical Standardization).

Three PROFIBUS variations exist today:

FMS (Fieldbus Messaging Specification)

DP (Decentralized Peripherals)

PA (Process Automation)

PROFIBUS/FMS is a powerful and complex multi-mastersystem.

The DP is a FMS reduced to one master system butoptimized for very short delay times.

PA is IEC Standard 1158-2.


8/21


PROFIBUS is restricted to a topological line structure(physical media), separated into several domains,coupled by repeaters.

There is no possibility to increase the number of nodes

beyond 32 so that RS-485 can be used. The protocols allow for 3-repeaters to be used in

series.

All masters are connected as a logical rings, realisedby a token.

Two priority levels are defined.


FieldBus based and Non-Fieldbusbased Configurations


CAN or Controller Area Network is an advanced serial bus systemthat efficiently supports distributed control systems

There are more than 150 million CAN nodes in use worldwide

CANBus nodes do not have a specific address but the identifiers ofthe transmitted messages which indicate the priority

Handle bus accesses by "Carrier Sense Multiple Access withArbitration on Message Priority" to avoid collisions of messages

Advantages :low cost as serial bus with two wires

reliable (sophisticated error detection and error handling mechanisms)erroneous messages are detected and repeatedhigh immunity to EMIallow multi-broadcastingunlimited number of nodes in principle

Introduction to CANBus


9/21


Controller Area Network - CANBus


CANBus

Once the node has gained access to the bus and istransmitting its message all other nodes become receivers.

Having received the message correctly, these nodes thenperform an acceptance test to determine if the data isrelevant to that particular node.

Not only possible to perform communication on a peer topeer basis but also to perform broadcast andsynchronized communication whereby multiple nodes canaccept the same message using only a singletransmission.

The ability to send data on an event basis means that busload utilization can be kept to a minimal amount.


A CAN message mainlyconsists of an identifierfield and the data field(plus error,acknowledgement andCRC fields). The identifier

field consists of 11 or 29bits (CAN 2.0A and 2.0Brespectively) and the datafield consists of amaximum of 8 bytes.


Ethernet

Ethernet is a shared local area networking(LAN) technology

Basic design consists of a sharedtransmission medium in the form of acoaxial cable or a multiport hub


10/21


Ethernet1970s developed by Xerox

Thicknet and Thinnet

10Base-2; 10 Base-5; 10Base-T; 100Base-T; 100VG-AnyLAN


Coaxialcable and

twisted-pairEthernetNetwork


10/100/1000 Base-T There are a number of adaptations to the IEEE

802.3 Ethernet standard, including adaptationswith data rates of 10 Mbits/sec; 100 Mbits/sec(Fast Ethernet); 1000 Mbits/sec (GigabitEthernet); and, most recently, 10 Gigabit/secEthernet


LonWorks - Virtual Wiring withNetwork Variables

Network variableconnection Virtual wire Created and changed

with a network tool Can be changed

withoutreprogramming

device Makes adds, moves,and changes easy

LightSwitch

Network Variable Connection


11/21


Network Tool Creates NV Connections

Network VariableConnection

DeviceDevice

Device

Device




The LonTalkProtocol: ANSI/EIA 709.1 Robust, field proven standardized protocol

High performance, low cost transceiversfor every application

A robust and comprehensive networkmanagement architecture

Complete suite of development tools

A reliable source of supply and service


Integration Made Easywith Standardization

LONMARK InteroperabilityAssociation Dedicated to the growth of

open, interoperable multi-vendor control systems

What they provide Interoperability design

guidelines Product conformance testing Marketing assistance

LONMARK

Logo


Manufacturers producing LonWorks Devices


12/21


X10 involving Power LineCarrier (120 kHz codedsignals on the powerline) - but noise on

power line is still a bigproblem

Echelon also provides powerline carrier DSP chip set forLonWorks

X-10 LampModule


X-10 signals are transmitted over the powerlineusing a 120kHz signal burst for 1 ms at the zerocrossing point of the 60Hz AC sine wave. This iswhere the least electrical noise is present.

A full X-10 transmission consists of 47 cycles and takesapproximately .8 seconds (60/47 and since 60 Hz is 60times per second that comes to0.78333).


1. To reduce errors, 2 zero crossings are required totransmit either a zero or one.

2. A binary one is represented by a 120kHz burst at thefirst crossing and no burst at the second.

3. A binary zero is represented by no burst at the first

and a 120kHz burst at the second crossing.


A basic X10 message consists of 13 bits:a 4-bit start code,a 4 bit-house code,a 4-bit unit/function code,and a 1 bit function bit.

The function bit indicates whether the previous 4 bits shouldbe interpreted as a unit code or a function code.

The start code uses 3 consecutive 120kHz bursts followedby no burst to differentiate itself from regular data bits (ituses half the usual # of cycles, hence each 13-bit messageactually uses only 11 AC cycles).

To turn on an X10 device will require two 13-bit messages,one to transmit the house & unit code address and anotherto transmit the command.


13/21


Every command is transmitted twice; however, receiversonly need to receive one of the commands to operate.The duplicate commands help ensure that the commandis received in the presence of noise.

The start code is equal to 1110. A receiver will need toreceive this code for two full sine waves before it beginsto monitor the power lines for an address code.

If the letter code matches, the receiver will compare thenext 5 bits of information - the number code.

When the number code matches, the receiver waits for afunction code. A delay of three cycles of the sine waveexist between the identification series of commands andthe function series of codes transmitted.


Letter CodesA = 0110; E = 0001; I = 0111; M = 0000; B = 1110;F = 1001; J = 1111; N = 1000; C = 0010; G = 0101;K = 0011; O = 0100; D = 1010; H = 1101; L = 1011;P = 1100.

Number Codes1 = 01100; 5 = 00010; 9 = 01110; 13 = 00000;2 = 11100; 6 = 10010; 10 = 11110; 14 = 10000;3 = 00100; 7 = 01010; 11 = 00110; 15 = 01000;4 = 10100; 8 = 11010; 12 = 10110; 16 = 11000.

Command CodesON = 00101; OFF = 00111; DIM = 01001;BRIGHT = 01011; ALL ON = 00011; ALL OFF = 00001.

51For internal use during lectures onlyInstabus from Siemens


EIB (European Installation Bus) is based on an electricalinstallation standard (instabus).

Siemens was in charge of the development of thecommunication chip, first version of the transmissiontechnology and the installation tools.

EIBA located in Brussels was founded for coordinatingcommon interests.


14/21


Physical layer is specified as a twisted pair line.Without a repeater, maximum length of STP is 1 km(otherwise 700 m).

Up to 64 devices can be connected to a physical

line. Twelve lines can be linked via Line Couplers to a

main line, such configuration called Area. Up to 15areas can communicate over a backbone bus viabackbone couplers.

Free topology (line, star, tree). Data transfer rate

over TP is fixed at 9600 bits/s. Other media includepower line, coaxial cable, infrared, radio frequencyand fiber optics.

Data link layer is CSMA/CA.54For internal use during lectures only

Maximum length of the protocol data unit is 23bytes.

The main focus of EIB is the electrical installationbusiness with some links to the home and buildingautomation business.


MODBUSCommunication on a MODBUS Network is initiated (started) by a "Master" witha "query" to a "Slave". The "Slave " which is constantly monitoring the networkfor "Queries" will recognise only the "Queries" addressed to it and will respondeither by performing an action (setting a value for example) or by returning a"response". Only the Master can initiate a query.

In the MODBUS protocol the master can address individual slaves, or, using a

special "Broadcast" address, can initiate a broadcast message to all slaves. TheIntegra products do not support the broadcast address.


Query by master:

Response by slave:


15/21


C-Bus from Clipsal58For internal use during lectures only



16/21


Brief Review on

Wireless Networks


Infrared Data Association

Established IrDA Standard

Direct sight of one another Angle of contact limited to 30 degree cone Length of transmission limited to 1 m Connects two PDAs together or a PDA to

a PC or fixed peripherals to a PC

4 Mbps (Standard IrDA) to 16 Mbps (FastInfrared) Serial Infrared Standard at 115 Kbps


HomeRF developed by HomeRF Working Groupled by Proxim partly owned by Intel

Other members include Compaq, Motorola and

Cayman Systems etc. Based on Shared Wireless Access Protocol

(SWAP) on unlicensed 2.4 GHz band 6 voice channels and 1 data channel based on

IEEE 802.11 wireless Ethernet standards 2 Mbps in principle, normally 1 Mbps SWAP Version 2.0 up to 10 Mbps Uses FHSS technology, 50 hops per second at

1 MHz intervals

Spread spectr m is a techniq e of spreading a signal o t o er


17/21


Spread spectrum is a technique of spreading a signal out overa very wide bandwidth, often over 200 times the bandwidth ofthe original signal.

In Direct Sequence Spread Spectrum (DSSS), the data totransmit is altered by a bit stream that is generated by the

sender. The bit stream represents every bit in the original data with

multiple bits in the generated stream, thus spreading the signalacross a wider frequency band.

If 100 bits are used to represent each bit of data, the signal isspread out to 100 times its original bandwidth.

It is called chipping code or processing gain.

A high processing gain increases the signals resistance tointerference. Minimum gain that FCC allows is 10 while mostcommercial products operate under 20.


In Frequency Hopping Spread Spectrum(FHSS), the original data is transmitted overa wide range of frequencies that change at

split-second intervals. Both the transmitter and receiver jump

frequencies in synchronization so a jammerwould have difficulty targeting the exactfrequency on which the devices arecommunicating.


Industrial, Scientific and Medical (ISM) bands are free for awireless product without obtaining an FCC license if theproduct meets certain requirements, such as operatingunder 1 W of transmitter output power.

902 MHz to 928 MHz, 26 MHz width

2.4 GHz to 2.4835 GHz, 83.5 MHz width

5.725 GHz to 5.85 GHz, 125 MHz width

The 2.4 GHz band is the only unlicensed band around thewhole world.


Wireless Ethernet CompatibilityAlliance (WECA) developedWi-Fi (Wireless Fidelity) basedon IEEE 802.11b standards

Supported by 3Com, Apple, Compaq, Lucentand Nokia etc.DSSS technology on unlicensed 2.4 GHz

band in three 17MHz channelsUp to 11 Mbps data transmission rate; a

substitute for wired EthernetNew IEEE 802.11a operates on 5 GHz bandup to 54 Mbps


18/21


HiperLAN began in Europe as EN 300652ratified in 1996 by

European Telecommunications Standards

Institute (ETSI) Broadband RadioAccess Network (BRAN) organization

HiperLAN/1 in 5GHz radio band, up to 24Mbps, for data, video, voice and image

transmission


ETSI is now developing HiperLAN/2, stillin 5GHz band, up to 54 Mbps

Major Competitor: IEEE 802.11a 802.11b


In 1997, Ericsson approached

IBM, Intel, Nokia and Toshiba toform Bluetooth Special Interest

Group (5 Founding Members) in1998

Bluetooth SIG released Version 1.0 ofBluetooth Specification in July, 1999

3Com, Lucent, Microsoft and Motorolajoined in 2000



19/21


Operating on unlicensed 2.40 GHz ISM band (actuallyfrom 2.4 GHz to 2.48 GHz) using FHSS technology

1600 hops /s among 79 1MHz intervals

Gross data transfer rate up to 1 Mbps

Three simultaneous synchronous (full-duplex) voicechannels and one asynchronous data channel (half-duplex)

Protection from interference and security of data

Two power levels defined (C3-1mW and C1-100 mW)

Supports both point-to-point and point-to-multipoint

connections (Piconets and Scatternets) Up to seven 'slave' devices can communicate with a

'master' radio in one device to form on Piconet


Currently , the 2.4 GHz band is used by:

2.4 GHz cordless telephones 802.11 wireless networks

HomeRF wireless networks Bluetooth devices Baby monitors Garage-door openers Urban and suburban wireless

communications systems including some

emergency radios Local government communications inJapan, France and Spain

Microwave ovens


Advantages of Wirelessover Wired Networks

Mobility

Installation inDifficult-to-Wire Areas

Increased Reliability Reduced Installation

Time

Long-Term Cost Savings


Major Applications of Wireless Networks

Retail Warehousing Healthcare Hospitals Old homes and small offices or home-

offices

Standalone houses, not suitable forapartments with hundreds of individualnetworks

Major Problems with Wireless Major Problems ith


20/21


Major Problems with WirelessNetworks

Multipath

propagation Path loss Radio Signal

Interference:inward andoutward


Major Problems withWireless Networks

Limited battery longevity System interoperability Application connectivity

Installation issues Health risks C1 OK, C3 mayhave problems if too many


Major Problems withWireless Networks

Security threats Security safeguards


ZigBee is a specification high level ommunicationprotocols using small, low-power digital radios basedon the IEEE 802.15.4-2003 standard for Low-RateWireless Personal Area Networks (LR-WPANs)

Technology defined by the ZigBee specification is

intended to be simpler and less expensive than otherWPANs, such as Bluetooth

ZigBee is targeted at radio-frequency (RF) applicationsthat require a low data rate, long battery life, andsecure networking

ZigBee operates in the industrial, scientific and

medical (ISM) radio bands; 868 MHz in Europe, 915MHz in the USA and Australia, and 2.4 GHz in mostjurisdictions worldwide

ZigBee protocols intended for embedded applications requiringlow data rates and low power consumption


21/21


low data rates and low power consumption

Resulting networks use very small amounts of power certifieddevices must have a battery life of at least two years

3 different types of ZigBee devices:

ZigBee coordinator (ZC): forms the root of the network tree andmight bridge to other networks; exactly one ZigBee coordinator ineach network since it is the device that started the networkoriginally

ZigBee Router (ZR): as well as running an application function, arouter can act as an intermediate router, passing on data fromother devices

ZigBee End Device (ZED): contains just enough functionality totalk to the parent node (either the coordinator or a router); itcannot relay data from other devices; thus longer battery life; leastamount of memory, and therefore less expensive


Discussion !

Documents

MEBS6005 Lecture 4 B&W.pdf