Hello,
I'm working on a gateway application that will disengage a real ecu and simulate in the software using CAN msgs for automotive.
Situation:
It looks like the CAN message has a count and a checksum as part of the payload, so every time I change a msg, i need to modify the counter recalculate the checksum.
Now in my msg, the checksum is at the 7th byte and the count is in the 8th byte. Ive added below some sample logs collected from the module. So I tried using an online CRC calculator to derive the Polynomial but I'm unable to arrive there. From the below logs, F9,F0,F6 and EE is the checksum. I'm trying to reverse engineer and validate what checksum method and polynomial was used, so that I can play and change the msgs. One more question I have is, while calculating the checksum (in this case), can I ignore the 7th byte(where checksum is inserted) and use the remaining 7 bytes including the count? I tried that route and used the standard CRC8, CRC8_SAE_J1850, CRC8_SAE_J1850_Zero but none that works.
6F 5A 6F 86 73 7C F9 70
6F 5A 6F 83 73 7E F9 71
6F 5D 6F 88 73 7D F0 73
6F 5C 6F 88 73 77 F6 74
6F 5D 6F 87 73 7E EE 75
I'm trying to implement this in LabVIEW and im using the XNET API's. This is kind of not so important now, i need to first identify and validate the checksum, I'm pretty confident with the implementation in LabVIEW.
Any help/leads would be helpful and appreciated.
Thanks
Jay