CAN Bus data rate and addressing

[steve-V8s]

Does the data rate used for in car can bus systems have any sort of standard or do different manufactures use whatever rate they think appropriate. The Can standard seems to define how it works but not the speed other than the upper speed limit.

Also are there any node addressing conventions for various functions or does each manufacturer make up its own standards. I guess if they are using mass produced can enabled light units or window winders, sensors etc they would be fairly standard across all cars they are used in.

[anonymous-user]

Typically CAN is split into two main automotive "standards" (which really aren't std at all!)

High speed = 500kbs
Low speed = 125kbs

With CAN low value message ID's win any arbitration (zero bits have automatic priority) so generally the more critical the message the lower its ID will be.

Most OE's will not be using extended ID's as a rule

Most OE's will have their own message databases, but some message id's will be common for two reasons:

1) legal requirement (OBD "scantool" and monitor completion data access
2) they use the same supplier systems (EPAS for example)

OE's generally have unique CCP message ID's (DTO/CRO) for each module on the bus (although all modules tend to report/return their presence on one overall "identify yourself" ID

[steve-V8s]

Thanks Max, just what I needed.