Jiří Novák, CTU FEE in Prague, Dept. of Measurement Industrial Distributed Systems Technology overview Technology overview Important features Important

Jiří Novák, CTU FEE in Prague, Dept. of Measurement

Industrial Distributed SystemsIndustrial Distributed Systems

• Technology overviewTechnology overview

• Important featuresImportant features

• ApplicationsApplications


ProgramProgram

• Centralized and distributed systemsCentralized and distributed systems

• ISO-OSI model, LANs and FieldbusesISO-OSI model, LANs and Fieldbuses

• Fieldbus configurationsFieldbus configurations

• Protocol layers, functionality and Protocol layers, functionality and implementationimplementation

• Important communication parameters, Important communication parameters, influence of external disturbancesinfluence of external disturbances

• Available standards and how to select the Available standards and how to select the right oneright one

• Interesting applicationsInteresting applications


Centralized SystemCentralized System

• complex wiringcomplex wiring

• low flexibilitylow flexibility

• higher sensitivity to higher sensitivity to disturbancesdisturbances

• all data processing all data processing on placeon place

• ““dumb” sensorsdumb” sensors

• data from sensors data from sensors are always availableare always available


Distributed SystemDistributed System

• simple wiringsimple wiring

• high flexibilityhigh flexibility

• higher immunity to higher immunity to external external disturbancesdisturbances

• intelligent sensors intelligent sensors and actuatorsand actuators

• data availability data availability limited by limited by communication communication parametersparameters


Communication PyramidCommunication Pyramid


Communication NetworksCommunication Networks


ISO - OSI ModelISO - OSI Model

LAN protocol LAN protocol layerslayers

Fieldbus protocol Fieldbus protocol layers layers


Protocol Layer InterfacesProtocol Layer Interfaces

Any layer provides Any layer provides services to the layer services to the layer and requests for and requests for services the layer services the layer belowbelow


LANsLANs Fieldbuses Fieldbuses

• High bit-ratesHigh bit-rates• Long framesLong frames• High overheadHigh overhead• Stochastic Medium Stochastic Medium

Access Control (Eth.)Access Control (Eth.)• Long or undefined Long or undefined

response timeresponse time• Error recovery Error recovery

implemented in implemented in softwaresoftware

• Designed for office Designed for office environmentenvironment

• Lower bit-ratesLower bit-rates• Short framesShort frames• Low overheadLow overhead• Deterministic Medium Deterministic Medium

Access ControlAccess Control• Short and defined Short and defined

response timeresponse time• Error recovery Error recovery

implemented in implemented in hardwarehardware

• Designed for Designed for industrial industrial environmentenvironment


ISO - OSI Model – Physical ISO - OSI Model – Physical LayerLayer defines the defines the

communication channel communication channel medium (wire, fiber …) medium (wire, fiber …) and its parameters (e.g. and its parameters (e.g. line impedance)line impedance)

defines connectors (not defines connectors (not typical in automotive typical in automotive industry)industry)

defines physical signaling defines physical signaling and channel codingand channel coding

defines modulation type defines modulation type and parameters (where and parameters (where applicable)applicable)


ISO - OSI Model – Link LayerISO - OSI Model – Link Layer

defines the way the defines the way the information is transmitted information is transmitted within the systemwithin the system

typically consists of two typically consists of two sublayers - MAC (Medium sublayers - MAC (Medium Access Control) and LLC Access Control) and LLC (Logical Link Control)(Logical Link Control)

defines the frame format, defines the frame format, error detection method, error detection method, addressing method …addressing method …


ISO - OSI Model – ISO - OSI Model – NetworkNetwork LayerLayer defines the way the defines the way the

information is transmitted information is transmitted among the systems - among the systems - routingrouting

typically it is not used in typically it is not used in local vehicle control local vehicle control networks networks

used in global networks used in global networks (the vehicle can be a (the vehicle can be a node)node)

IP (Internet Protocol) can IP (Internet Protocol) can be an examplebe an example


ISO - OSI Model – ISO - OSI Model – TransportTransport LayerLayer it can change the it can change the

communication fromcommunication from connectionless to connectionless to

connection orientedconnection oriented

unreliable to reliableunreliable to reliable

not used in local vehicle not used in local vehicle control networkscontrol networks


TCP (Transmission Control TCP (Transmission Control Protocol) can be an Protocol) can be an exampleexample


ISO - OSI Model – ISO - OSI Model – SessionSession LayerLayer creates, controls and creates, controls and

discards sessionsdiscards sessions

not used in local vehicle not used in local vehicle control networkscontrol networks


example:example: Internet access from the Internet access from the

car requires to create and car requires to create and keep the session between keep the session between the local node and the local node and Internet providerInternet provider


ISO - OSI Model – Presentation ISO - OSI Model – Presentation LayerLayer it codes and decodes datait codes and decodes data

forfor the communicating the communicating parties to understand parties to understand each othereach other

byte orderingbyte ordering

numbers codingnumbers coding

character codingcharacter coding example:example: the text recoding is the text recoding is

required if two nodes use required if two nodes use different internal different internal character coding (e.g. character coding (e.g. ASCII and UNICODE)ASCII and UNICODE)


ISO - OSI Model – Application ISO - OSI Model – Application LayerLayer provides high-level provides high-level

services for application services for application programsprograms

• write variablewrite variable

• read variableread variable

• ……..


Typical Fieldbus ConfigurationsTypical Fieldbus Configurations

• Bus - CAN, Profibus, Bitbus, FoundationBus - CAN, Profibus, Bitbus, Foundation

Fieldbus, Measurement Bus Fieldbus, Measurement Bus



• Tree - AS Interface Tree - AS Interface



• Ring - Interbus, P-Net Ring - Interbus, P-Net


Physical Layer ProtocolsPhysical Layer Protocols

• Physical topologyPhysical topology

• Physical medium, connectors Physical medium, connectors

• Signaling levelsSignaling levels

• Channel coding, bit stuffingChannel coding, bit stuffing

• Transmitter and receiver parametersTransmitter and receiver parameters

• Segment lengthSegment length

• Number of repeatersNumber of repeaters


Link Layer ProtocolsLink Layer Protocols• MAC - Medium Access ControlMAC - Medium Access Control

• Master - SlaveMaster - Slave• Bus ArbiterBus Arbiter• Token PassingToken Passing• CSMACSMA

• LLC - Logical Link ControlLLC - Logical Link Control• Frame encodingFrame encoding• Error checkingError checking• Receipt confirmationReceipt confirmation• AddressingAddressing


Link Layer AddressingLink Layer Addressing

• Node oriented addressingNode oriented addressing

• Profibus, Measurement Bus, AS InterfaceProfibus, Measurement Bus, AS Interface

• Message oriented addressingMessage oriented addressing

• CAN - CANopen, Device NetCAN - CANopen, Device Net

• I/O frame oriented addressingI/O frame oriented addressing

• InterbusInterbus


Link Layer Error CheckingLink Layer Error Checking

• Frame format errorsFrame format errors

• delimitersdelimiters

• defined value bitsdefined value bits

• Information bits errorsInformation bits errors

• CRC, parity check, check sumCRC, parity check, check sum

• Channel Coding errorsChannel Coding errors

• bit stuffing errorsbit stuffing errors


Application Layer ProtocolsApplication Layer Protocols

• Remote serviceRemote service


Application Layer ProtocolsApplication Layer Protocols

• Local serviceLocal service


User Layer ProtocolsUser Layer Protocols

• Communication and Device Communication and Device ProfilesProfiles

• Special control framesSpecial control frames

• Timing framesTiming frames

• Device objectsDevice objects

• Number and types Number and types

• Access permissionsAccess permissions


Well Known Fieldbus StandardsWell Known Fieldbus Standards• CAN (CANopen, Device Net, SDS)CAN (CANopen, Device Net, SDS)• Foundation FieldbusFoundation Fieldbus• Profibus Profibus • LONLON• BITBUSBITBUS• InterbusInterbus• ASIASI• HARTHART• M BusM Bus• Measurement BusMeasurement Bus


How to Select a Suitable How to Select a Suitable Fieldbus?Fieldbus?

• New project or reconstructionNew project or reconstruction

• Type of the automation taskType of the automation task

• Components availabilityComponents availability

• Future extension possibilitiesFuture extension possibilities

• Total system costsTotal system costs

• Environmental parameters Environmental parameters

• Open standard or proprietary solutionOpen standard or proprietary solution


Interesting ApplicationsInteresting Applications

• Car systems control (CAN)Car systems control (CAN)

• Building automation (LON, EIB)Building automation (LON, EIB)

• Petrol station automation (EPSI)Petrol station automation (EPSI)

• Utility meters (Meter Bus)Utility meters (Meter Bus)

• Airplane systems control (Arinc)Airplane systems control (Arinc)

Documents

Jiří Novák, CTU FEE in Prague, Dept. of Measurement Industrial Distributed Systems Technology overview Technology overview Important features Important