Custom CAN address mapping

[testerpresent]

Hey all,

I checked the docs and saw 4.3.3 PCAN-UDS 2.x Example on how to configure custom mapping for an ECU, but I was wondering does it exist in the UDS protocol a way to generate this mapping runtime, probably based on some request/response to the CAN gateway that gives you what is actually available on the line? I am trying to emulate a tester, and looking at some products it looks like they generate the list of active ECUs on the fly, but I might be wrong.

I would apprecaite some information to get me started and I might be able to provide better description of what I am actually tring to do

Best regards!

[F.Vergnaud]

Hello,

UDS protocol does not include this kind of feature: there is no specification regarding a discovery protocol.
However you could implement it the same way it is done by IP scanners:

• make UDS TesterPresent requests on a range of CAN IDs,

• if you get a response for a request then you discovered a physical UDS request/response couple.

• if you get several responses for a request then you discovered a functional UDS request and some corresponding ECU responses.

Note: if your CAN bus only have one ECU, it may be difficult to distinguish functional/physical requests.

[testerpresent]

Hello Fabrice,

Thank you for the quick reply and explanation, i reached the same solution with the Tester Present broadcast request, but I am still digging into docs to udnerstand it better.
Can you elaborate a bit on what is the idea to have only 8 physical ecu addresses (for example in normal 11bit mode) when there might be a lot more ECUs connected on the line? Does it mean that the different vehicle systems are grouped behind these 8 physical addresses always or this is just manufacterers decision at the time of production?

Best regards!

[K.Wagner]

Hello,

Can you elaborate a bit on what is the idea to have only 8 physical ecu addresses (for example in normal 11bit mode) when there might be a lot more ECUs connected on the line?

Please note that this question is pure related to the UDS protocol itself and not to our API. The 8 physical addresses are like this per norm definition - we do not know the background. Also note that the support we give is for API using. Unfortunatelly, explaining the protocol itself and how it works is out of scope.

Thanks for your understanding.

[testerpresent]

Hello,

Can you elaborate a bit on what is the idea to have only 8 physical ecu addresses (for example in normal 11bit mode) when there might be a lot more ECUs connected on the line?

Please note that this question is pure related to the UDS protocol itself and not to our API. The 8 physical addresses are like this per norm definition - we do not know the background. Also note that the support we give is for API using. Unfortunatelly, explaining the protocol itself and how it works is out of scope.

Thanks for your understanding.

Yes, of course!
Thank you for your answer!

[PEAK-Support]

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