1 / 19

CANopen

CANopen. History CANopen and the ISO model Physical layer Link layer Application layer Profiles Strengths - Weaknesses. History. 1980-1983: Creation of CAN as an initiative by the German equipment manufacturer BOSCH to meet a requirement in the automotive industry .

olin
Download Presentation

CANopen

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CANopen History CANopen and the ISO model Physical layer Link layer Application layer Profiles Strengths - Weaknesses

  2. History • 1980-1983: Creation of CAN as an initiative by the German equipment manufacturer BOSCH to meet a requirement in the automotive industry. CAN only defines one part of layers 1 and 2 of the ISO model. • 1983-1987: The prices of drivers and micro-controllers featuring CAN become very attractive as they are used in high volume in the automotive industry. • 1991: CIA = CAN in Automation is born: http://www.can-cia.de/to promote industrial applications.

  3. History • 1993: CAL = CAN Application Layer specifications published by CiA describing transmission mechanisms but not when and how to use them. • 1995: CiA publishes the DS-301 communication profile: CANopen • 2001: CiA publishes DS-304 which can be used to integrate level 4 safety components on a standard CANopen bus (CANsafe).

  4. CANopen and the ISO model Device Profile CiA DSP-401 I/O modules Device Profile CiA DSP-402 Drives Device Profile CiA DSP-404 Measuring devices Device Profile CiA DSP-4xx CANopen is based on CAL 7 APPLICATION CiA DS-301 = Communication profile CAL= CAN Application Layer 6 PRESENTATION EMPTY EMPTY 5 SESSION 4 TRANSPORT EMPTY 3 NETWORK EMPTY CAN 2.0 A and B + ISO 11898 2 LINK = LLC + MAC 1 PHYSICAL CAN 2.0 A and B = ISO 11898-1 and 2 ISO 11898 + DS-102

  5. Physical layer Medium: Shielded twisted pair2 or 4-wire (if power supply) Topology: Bus type With short tap links and 120 ohm line termination resistor Maximum distance: 1000 m Speed: 9 possible speeds from 1 Mbps to 10 KbpsDepends on bus length and cable type: 25 m at 1 Mbps, 1000 m at 10Kbps Max. no. of devices: 128 1 master and 127 slaves

  6. Connectors CiA recommendation DR-303-1 includes a list of suitable connectors divided into 3 categories with a description of their pin configuration. 9-pin SUB D DIN 41652 RJ45 Open style 5-pin Micro Style = M12 ANSI/B93.55M-1981 Male, product side

  7. Example architecture Premium TEGO POWER TEGO POWER ATV58 ATV58 Line termination resistor Line termination resistor (120 ) FTB1CN FTB1CN Line termination resistor

  8. Link layer Medium access method: CSMA/CA Every device may send data as soon as the bus is free. The principle of dominant and recessive bits enables non-destructive bit-by-bit arbitration in the event of a collision. The priority of a message is indicated by the value of the identifier. The identifier with the lowest value has priority. On CANopen the identifier value depends on the address of the product and which type of message is transmitted (process data, service data, synchronization message…)

  9. Structure of the CAN frame Arbitration field Frame size without bit stuffing: 47 to 111 bits 1 11 1 6 0 to 64 15 1 1 1 7 Data field CRC delimit. ACK delimit. RTR Remote Transmission Request bit Start of frame (SOF) CRC sequence ACK slot End of frame (EOF) Identifier Control field: compatibility and length

  10. Dominant and recessive bits Identifier Controlfield SOF RTR 10 9 8 7 6 5 4 3 2 1 0 R Station 1 loses arbitration Station 1 D Station 2 Station 2 loses arbitration Station 3 S2 S3 S1

  11. Link layer Communication model: Producer/Consumer An identifier coded on 11 bits and located at the start of the message informs the receivers about the type of data contained in each message. Each receiver decides whether or not to accept the data. This concept permits multiple communication models : Transmission on change of state, cyclic, SYNC signal, on Remote frame (Master/Slave).

  12. Link layer Max. size of useful data: 8 bytes per frame Transmission security: One of the best local industrial networksNumerous signalling and error detection devices ensure high transmission security.

  13. Application layer 4 types of standardized service: 1 . Network administration: Parameter settings, start-up, monitoring (master-slaves) 2 . Transmission of low-volume process data (<= 8 bytes) in real time: PDO = Process Data Object (producer-consumer) PDOs can be transmitted on changes of state, cyclically, on receipt of the SYNC message or at the request of the master. 3 . - Transmission of high-volume parameter data (> 8 bytes) by segmentation without time restrictions: SDO = Service Data Object (client-server) 4 . Predefined messages for managing synchronization (SYNC), time-based references, fatal errors: SFO = Special Function Object

  14. Application layer CANopen defines: howdata is transmitted: DS-301 communication profilecommon to all products Amongst other things this defines the allocation of COB-ID identifiers for each type of message. what data is transmitted: DS-4xx product profilesspecific to each product family (discrete I/O, analogue I/O, variable speed drives, encoders, etc.) These functions are described by means of a Device Object Dictionary : OD

  15. Object Dictionary = OD The object dictionary OD is a sequenced group of objects that can be accessed by means of: • a 16-bit index • and in some cases an 8-bit sub-index It describes all the functions of the product. This description takes the form of an EDSfile(Electronic Data Sheet) in ASCII format. This has a strict syntaxand can be used by the bus configurators (Sycon etc.)

  16. Structure of the “Object Dictionary”

  17. Allocation of default identifiers With the aim of reducing the network configuration phase a compulsory system for allocating default identifiers has been defined. This allocation occurs in the "Pre operational" state just after the initialization phase. It is based on dividing the COB-ID identifier into 2 parts: Function code is used to code 2 PDOs in receive mode, 2 PDOs in transmit mode, 1 SDO, 1 EMCY object, 1 Node Guarding Identifier, 1 SYNC object, 1 Time Stamp object and 1 node guarding. Node ID corresponds to the product address coded by DIP switches, for example. 10 9 8 7 6 5 4 3 2 1 0 Function Code Node ID

  18. Allocation of default identifiers Allocation of default identifiers can be used on products which support the first 4 PDOs. (The fifth PDO overlaps the area reserved for SDO) 1024 identifiers maximum reserved for PDOs.

  19. Strengths - Weaknesses Strengths • Cost of connection point • Wide selection of drivers • Interference resistant • Open protocol • Flexibility Weaknesses • Bus length at 1 Mbps = 25 m • Level of integration in PL7 • Current Schneider offer • Non-deterministic

More Related