|CAN/CAN FD seminar||2016-09-28||Nuremberg, DE||Deutsch|
|CANopen seminar||2016-09-29||Nuremberg, DE||Deutsch||Register now|
|CAN 2020 event||2016-10-06||Lyon, FR||English||Register now|
|CAN/CAN FD seminar||2016-10-18||Antwerpen, BE||English||Register now|
|CANopen seminar||2016-10-19||Antwerpen, BE||English||Register now|
* Subject to change without notice.
Mapping of J1939 to CAN FD
CiA has released the CiA 602-2 specification internally as a Draft Standard Proposal (DSP). It describes the mapping of J1939 and other commercial vehicle communication standards to CAN FD data frames.
CiA 602-2 mainly specifies how to map the existing J1939 parameter groups to CAN FD data frames with data fields up to 64 byte. The basic idea is simple: The 8-bit J1939 source address is mapped into the CAN identifier. The CAN FD data field contains multiple so-called C-PDUs (contained protocol data unit). The C-PDU itself is structured using a 32-bit header and a payload of up to 60 byte. The type of C-PDU is indicated by a type-of-service information given in the header. Most important is the J1939 C-PDU, which provides the J1939 PDUS and J1939 PDUF information as well as an 8-bit payload length indication in the header. This approach complies with Autosar requirements.
Today, the J1939 parameter group is restricted to a length of 8 byte. CiA 602-2 allows adding an optional safety and security field or a combination of both. In the future, J1939 parameter groups with other lengths could also be defined, but this will not be the job of CiA. The CiA 602-2 protocol has already been approved in a practical test by Vector and ZF in a real truck.
A more detailed article has been published in the June 2016 issue of the CAN Newsletter. The CiA 602-2 specification is available to all CiA members. OEMs may request a personalized copy by email (service(at)can-cia.org).
CAN FD standards and recommendations
Since end of last year, the second edition of ISO 11898-1 is published. It standardizes the CAN FD protocol as well as the Classical CAN protocol. The standard contains what the chipmakers need to implement the protocols in silicon.
The transceiver chips qualified for bit-rates of 1 Mbit/s and higher are standardized in ISO 11898-2:2016. ISO will publish the document within the next months. Additionally, ISO will release conformance test plans for ISO 11898-1:2015 (ISO 16845-1) and for high-speed CAN transceivers (ISO 16845-2). Both test standards will be available by end of the year.
However, implementing CAN (FD) controller and CAN transceivers is just one part of the story. Device (ECU) and network design rules, recommendations, and specifications are needed to make life easier for CAN users. CiA develops the CiA 601 series providing recommendations for node and network designs. CiA 601-2, recommendation for CAN controller host interfaces, is close to be released. The CiA 603 document is intended to harmonize the time stamping of Classical CAN and CAN FD messages.
SAE has developed the J2284-4 and J2284-5 recommended practices for passenger cars. Part 4 specifies a CAN line topology for 500 kbit/s (arbitration) and 2 Mbit/s (dataphase). Part 5 is suitable for dataphase bit-rates up to 5 Mbit/s and a point-to-point communication. These documents are guidelines for OEMs and Tier 1 supplier.
CiA works on the CiA 602 series for commercial vehicles and off-highway vehicles. Part 2 specifies the mapping of J1939 parameter groups to CAN FD frames. The network design including the physical layer is not yet finalized.
In general, the CiA technical groups need to know the requirements for the desired CAN FD networks – from members and non-members. Please feel free to contact us by email service(at)can-cia.org.
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If you are looking for CAN-related products, you could visit the CAN Newsletter Online and the CiA Product Guide. Both publications provide brief product information. The product guides are structured according to a nomenclature in order to make it as easy as possible to find the desired product information. The online magazine reports recently launched CAN products.
If you would like to be informed on published news in any of CiA’s media, we recommend subscribing to CiA’s Weekly Telegraph, distributed by email.