Industrial Distributed Systems

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

2. Program • Centralized and distributed systems • ISO-OSI model, LANs and Fieldbuses • Fieldbus configurations • Protocol layers, functionality and implementation • Important communication parameters, influence of external disturbances • Available standards and how to select the right one • Interesting applications Jiří Novák, CTU FEE in Prague, Dept. of Measurement

3. Centralized System • complex wiring • low flexibility • higher sensitivity to disturbances • all data processing on place • “dumb” sensors • data from sensors are always available Jiří Novák, CTU FEE in Prague, Dept. of Measurement

4. Distributed System • simple wiring • high flexibility • higher immunity to external disturbances • intelligent sensors and actuators • data availability limited by communication parameters Jiří Novák, CTU FEE in Prague, Dept. of Measurement

5. Communication Pyramid Jiří Novák, CTU FEE in Prague, Dept. of Measurement

6. Communication Networks Jiří Novák, CTU FEE in Prague, Dept. of Measurement

7. ISO - OSI Model Fieldbus protocol layers LAN protocol layers Jiří Novák, CTU FEE in Prague, Dept. of Measurement

8. Protocol Layer Interfaces Any layer provides services to the layer and requests for services the layer below Jiří Novák, CTU FEE in Prague, Dept. of Measurement

9. High bit-rates Long frames High overhead Stochastic Medium Access Control (Eth.) Long or undefined response time Error recovery implemented in software Designed for office environment Lower bit-rates Short frames Low overhead Deterministic Medium Access Control Short and defined response time Error recovery implemented in hardware Designed for industrial environment LANs Fieldbuses Jiří Novák, CTU FEE in Prague, Dept. of Measurement

10. ISO - OSI Model – Physical Layer • defines the communication channel medium (wire, fiber …) and its parameters (e.g. line impedance) • defines connectors (not typical in automotive industry) • defines physical signaling and channel coding • defines modulation type and parameters (where applicable) Jiří Novák, CTU FEE in Prague, Dept. of Measurement

11. ISO - OSI Model – Link Layer • defines the way the information is transmitted within the system • typically consists of two sublayers - MAC (Medium Access Control) and LLC (Logical Link Control) • defines the frame format, error detection method, addressing method … Jiří Novák, CTU FEE in Prague, Dept. of Measurement

12. ISO - OSI Model – Network Layer • defines the way the information is transmitted among the systems - routing • typically it is not used in local vehicle control networks • used in global networks (the vehicle can be a node) • IP (Internet Protocol) can be an example Jiří Novák, CTU FEE in Prague, Dept. of Measurement

13. ISO - OSI Model – Transport Layer • it can change the communication from • connectionless to connection oriented • unreliable to reliable • not used in local vehicle control networks • used in global networks (the vehicle can be a node) • TCP (Transmission Control Protocol) can be an example Jiří Novák, CTU FEE in Prague, Dept. of Measurement

14. ISO - OSI Model – Session Layer • creates, controls and discards sessions • not used in local vehicle control networks • used in global networks (the vehicle can be a node) • example: Internet access from the car requires to create and keep the session between the local node and Internet provider Jiří Novák, CTU FEE in Prague, Dept. of Measurement

15. ISO - OSI Model – Presentation Layer • it codes and decodes dataforthe communicating parties to understand each other • byte ordering • numbers coding • character coding • example: the text recoding is required if two nodes use different internal character coding (e.g. ASCII and UNICODE) Jiří Novák, CTU FEE in Prague, Dept. of Measurement

16. ISO - OSI Model – Application Layer • provides high-level services for application programs • write variable • read variable • …. Jiří Novák, CTU FEE in Prague, Dept. of Measurement

17. Typical Fieldbus Configurations • Bus - CAN, Profibus, Bitbus, Foundation Fieldbus, Measurement Bus Jiří Novák, CTU FEE in Prague, Dept. of Measurement

18. Typical Fieldbus Configurations Tree - AS Interface Jiří Novák, CTU FEE in Prague, Dept. of Measurement

19. Typical Fieldbus Configurations Ring - Interbus, P-Net Jiří Novák, CTU FEE in Prague, Dept. of Measurement

20. Physical Layer Protocols Physical topology Physical medium, connectors Signaling levels Channel coding, bit stuffing Transmitter and receiver parameters Segment length Number of repeaters Jiří Novák, CTU FEE in Prague, Dept. of Measurement

21. Link Layer Protocols • MAC - Medium Access Control • Master - Slave • Bus Arbiter • Token Passing • CSMA • LLC - Logical Link Control • Frame encoding • Error checking • Receipt confirmation • Addressing Jiří Novák, CTU FEE in Prague, Dept. of Measurement

22. Link Layer Addressing • Node oriented addressing • Profibus, Measurement Bus, AS Interface • Message oriented addressing • CAN - CANopen, Device Net • I/O frame oriented addressing • Interbus Jiří Novák, CTU FEE in Prague, Dept. of Measurement

23. Link Layer Error Checking • Frame format errors • delimiters • defined value bits • Information bits errors • CRC, parity check, check sum • Channel Coding errors • bit stuffing errors Jiří Novák, CTU FEE in Prague, Dept. of Measurement

24. Application Layer Protocols Remote service Jiří Novák, CTU FEE in Prague, Dept. of Measurement

25. Application Layer Protocols Local service Jiří Novák, CTU FEE in Prague, Dept. of Measurement

26. User Layer Protocols • Communication and Device Profiles • Special control frames • Timing frames • Device objects • Number and types • Access permissions Jiří Novák, CTU FEE in Prague, Dept. of Measurement

27. Well Known Fieldbus Standards CAN (CANopen, Device Net, SDS) Foundation Fieldbus Profibus LON BITBUS Interbus ASI HART M Bus Measurement Bus Jiří Novák, CTU FEE in Prague, Dept. of Measurement

28. How to Select a Suitable Fieldbus? New project or reconstruction Type of the automation task Components availability Future extension possibilities Total system costs Environmental parameters Open standard or proprietary solution Jiří Novák, CTU FEE in Prague, Dept. of Measurement

29. Interesting Applications • Car systems control (CAN) • Building automation (LON, EIB) • Petrol station automation (EPSI) • Utility meters (Meter Bus) • Airplane systems control (Arinc) Jiří Novák, CTU FEE in Prague, Dept. of Measurement