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CAN FD recommendations

Device physical and CAN FD controller interfaces

CiA has released the CiA 601-1 and CiA 601-2 documents, which have been developed jointly by OEMs, Tier1s, and CAN FD chipmakers.

In order to achieve interoperability between CAN FD devices, physical layer guidelines are necessary (Photo: CiA)

CiA 601-1 recommends the physical layer design for CAN FD device interfaces. It is based on the ISO 11898-2:2016 standard, which specifies the CAN FD transceivers. The 16-pages document deals with what is not covered by the ISO standards, in particular the symmetry issues of the other interface components. This includes also the transceiver loop-delay, the transceiver TX delay, and RX delay symmetries as well as the transmitter delay. CiA 601-1 doesn’t cover system design recommendations; they will be given in CiA 601-3, which is still under development. The CiA 601-4 ringing suppression circuitry specification for CAN FD networks is under review and will be released soon as version 2.0.

“The updated ISO 11898 series standardizes the CAN controller including CAN FD in Part 1 and the CAN media access unit in Part 2,” explained Holger Zeltwanger, CiA Managing Director and Convenor of the responsible ISO working group. “The device and system design recommendations and specifications are developed within the CiA organization until they are mature enough to be submitted to ISO.” In the CiA Interest Group CAN FD, chaired by Dr. Arthur Mutter (Bosch), representatives from relevant chipmakers, some ECU providers, and mainly German OEMs develop jointly the design recommendations and specifications for CAN FD devices and network systems. The group is also responsible to organize CAN FD plugfests, in which the interoperability of implementations is tested.

CiA 601-2 provides guidelines for the CAN controller interface to the host controller. Besides special states and modes, it recommends the control and status interface, the bit-timing configuration parameters including those for the secondary sample-point. The 16-pages document doesn’t specify the time-stamping functionality. This is done in CiA 603, which will be released soon. All CAN FD related recommendations and specifications are free-of-charge for CiA members as all other CiA technical documents. Non-members have to pay a lump sum of € 499 plus German VAT (value added taxes).


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CAN in Automation