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CAN in Automation

Interest Group ‘Commercial Vehicles’

CiA members have established an Interest Group (IG). The group will develop recommendations and specifications for CAN FD networks used in commercial vehicles.

European truck companies already have started to pre-develop in-vehicle networks based on CAN FD (Photo: Daimler)

THE IG COMMERCIAL VEHICLES WILL RECOMMEND physical layer options for CAN FD networks. It intents to specify a star topology using a data-phase bit-rate of 2 Mbit/s. Additionally, a line topology will be defined for data-rates up to 4 Mbit/s. For this approach a daisy-chain connections is recommended.

The IG will also specify an application layer, which makes use of the Parameter Groups (PG) as defined in SAE J1939-71. It was proposed to map several PGs into one CAN FD data frame with a header comprising the PGN (parameter group number) and for future flexibility length information. These PDUs should be compliant to Autosar, in order to simplify the development of communication technology independent software. The application layer will use the ISO transport protocol as defined in 15675-2, and will also include specifications for diagnostics, in particular UDS (Unified Diagnostic Services). “The IG will not re-invent the wheel,” said Holger Zeltwanger, CiA Managing Director. “The experts will make references as much as possible to existing standards and specifications.” When the recommendations and specifications are stable and mature, they will be submitted to SAE for further development and maintenance.

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