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CAN in Space Workgroup Report

This presentation provides an overview of the history, objectives, planning, and status of the CAN technology adaptation for spacecraft. It includes key CANOpen features and resources for space integration.

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CAN in Space Workgroup Report

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  1. CAN in Space Workgroup Status Report L. Stagnaro & P. Roos

  2. Presentation overview • History • Workgroup Objectives & Planning • Status • Overview of key CANOpen features • CANOpen add-ons for space adaptation • Resources & Contact Points ESTEC 5-7 May 2003

  3. History • Since the start of the SMART-1 spacecraft development and the development of the ESA free CAN core (Hurricane), CAN technology had raised increasing interest in the European aeronautic industry • Standard CAN needs to be completed with an high level protocol and an electrical interface before it can be used onto a spacecraft ESTEC 5-7 May 2003

  4. History Cont’d • There was the need to provide guidelines for the use of CAN in ESA missions, in order to standardize its use and prevent the proliferation of dialects and custom solutions. • It was decided to start a workgroup formed by member of ESA, Industry and Academia to provide the needed recommendations. ESTEC 5-7 May 2003

  5. Workgroup Objectives • Selection of high level protocol industrial standard that most suit the spacecraft on-board applications. • Definition of the electrical/physical interface that fulfill the requirements of a spacecraft avionics. • Definitions of a selected number of features to complete the standard in aspects that are specific of a spacecraft avionics such as redundancy. ESTEC 5-7 May 2003

  6. Workgroup Objectives Cont’d • The working group will complete the task in one year time frame. • The product of the working group will be a set of recommendations that will become part of the ECSS standard. (1st Draft of recommendation available) ESTEC 5-7 May 2003

  7. Selection Implementation Validation Workgroup Planning (1) CAN Workshop (Dec 2002) 1st Meeting (5-6 March 2003) 2nd Meeting 3rd Meeting 4th Meeting • Task • Preliminary definition of services • Demonstrator specification • Physical Layer requirements definition • Output • 1st Draft available • Demonstrator Specification ESTEC 5-7 May 2003

  8. Selection Implementation Validation Workgroup Planning (2) CAN Workshop (Dec 2002) 1st Meeting (5-6 March 2003) 2nd Meeting 3rd Meeting 4th Meeting • Task • Consolidate the selected services • Implement services in demonstrator • Output • 2nd Draft of recommendation ESTEC 5-7 May 2003

  9. Selection Implementation Validation Workgroup Planning (3) CAN Workshop (Dec 2002) 1st Meeting (5-6 March 2003) 2nd Meeting 3rd Meeting 4th Meeting • Task • Implement services in demonstrator (cont’d) • Validation tests including physical layer • Define Device Profiles for typical S/C equipments • Output • Draft Device Profiles • 3rd Draft of recommendation ESTEC 5-7 May 2003

  10. Selection Implementation Validation Workgroup Planning (4) CAN Workshop (Dec 2002) 1st Meeting (5-6 March 2003) 2nd Meeting 3rd Meeting 4th Meeting • Task • Implement and validate Device Profiles • Finalisation of the tests and simulations • Finalisation of draft recommendation • Output • Final draft of recommendation ESTEC 5-7 May 2003

  11. CANOpen • After an initial investigation among the industry standard protocol the CANOpen has been selected. • From the CAN Justification file • CANOpen seems definitively the most advanced/flexible among the analysed protocols, supporting many needed functions. In addition the capability of configuring a node is attractive for inter-operability of units ESTEC 5-7 May 2003

  12. CAN Industrial presence ESTEC 5-7 May 2003

  13. CANOpen at a glance • Two main communication objects • SDO (Service Data Object) for transfer of complex and large data • PDO (Process Data Object) for simple or short real-time communication • Node Object dictionary • Allow the configuration of a unit for the specific network • Contains information about the unit capabilities • Device profiles • Sync message for cyclic coordination • High accuracy time distribution (~1 us) • Defined Node and Error Handling • Defines Node state machines • Predefined error codes • Specific Unit Codes ESTEC 5-7 May 2003

  14. CANOpen Object Dictionary • An object dictionary is a node shared memory area that can be read/written by any other node on the network • To understand node type, capabilities and messages structure (READ) • To configuring the node for the network in which the node is inserted, as for example the data period. (WRITE) • A mandatory set of entry in the dictionary is established by the standard device profile to which the node belongs. ESTEC 5-7 May 2003

  15. Entry Type Parameter Data Length Mode Set of defined Parameter By the unit manufactures 0 VAR Scaling rad/sec per byte BYTE R/W R/W 1 VAR Low Pass Filter Frequency BYTE R 2 VAR Gyro 1 rate WORD Message Entry Parameter Entry Data Length Mapping To Write Messages A 1 0 BYTE A 2 1 BYTE User Configured Mapping To Read Messages Message Entry Parameter Entry Data Length B 3 2 WORD Cyclic At every Sync CANOpen Dictionary Example • Device Profile: AOC Sensor/Actuators Interface ESTEC 5-7 May 2003

  16. SYNC SYNC SYNC Event time Cyclic Acyclic CANOpen Sync • Transmission type • Event driven (spontaneous) • Polled • Synchronous cyclic or acyclic ESTEC 5-7 May 2003

  17. reset Initialization Pre-operational Stopped Operational CANOpen Network Management • CANOpen defines a set of services to startup the network before commencing the nominal work of the system. • During the network startup each node is configured (if needed) and take to the operational state. Reset of Settings Configuration of the device Device Operation Stop of all communication ESTEC 5-7 May 2003

  18. Large Data Unit Transfers Optional protocol compatible with CANOpen Co-exists with CANOpen Reduced overhead compared to CANOpen Physical Layer Shall be suitable for vast majority of missions Insure device-on-bus electrical compatibility and device-across-the-industry electrical compatibility Redundancy Management of bus redundancy Informative examples to be put in recommendation annex Relationship between CANOpen Node State Diagram and redundancy Hot/cold bus and node redundancy Add-on to CANOpen ESTEC 5-7 May 2003

  19. Physical Layer • Mandatory • ISO-11898: 1993 (Automotive) and ISO 11898 Amendment 1:1995 • Up to 1Mbps – CAN Hi-speed • Recommendation • Number of Nodes: 32 Minimum • Bus cabling ISO 11898 compliant • Connector types • Optional • Single-point failure tolerant/Dual Redundant I/F • High Speed Optical coupler • Power thru CAN bus connector ESTEC 5-7 May 2003

  20. Resources • Yahoo group page: • http://groups.yahoo.com/group/CAN_Space/ • Discussion forum • Web page: • http://users.skynet.be/cotectic/CAN-WG/ • Draft recommendation • Minutes of Meetings etc. related to the CAN WG activities. ESTEC 5-7 May 2003

  21. Contact Persons • Luca Stagnaro (Chairman) • luca.stagnaro@esa.int • Peter Roos (Secretary) • peter.roos@esa.int • Rodger Magness (Physical Layer) • rodger.magness@esa.int • Patrick Plancke (Head of Computer & Data Systems section) • patrick.plancke@esa.int ESTEC 5-7 May 2003

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