J1939 receiving messages greater than 8 bytes

[SierraCP]

Hi,

I am trying to read DTC information from an ECU, however the DM1 message is currently 62bytes in length. Because of this the message is being ignored and filtered out (can't see message with the bus monitor either).

According to the provider of the ECU the DM1 message is not transmitted as a BAM or transfer protocol, but varies in size with varying numbers of DTC faults.

I assumed that all CAN bus data could not be greater than 8 bytes in length, but apparently this ECU does.

Note: The 62 byte DM1 message can be seen if CANalyzer is used with a propriety CAN interface.

Regards

Kevin

[Chris_Jones_NIUK]

Hi Kevin,

Welcome to the NI Discussion Forums!

Could I ask you a little more information in order to understand the issue:

-Could you clarify the make/model of the ECU? 

-In order to send data of length greater than 8 bytes, this must be sent in multiple packets. Did the provider say that this was not the case?

-Did the provider also say that 'Connection Mode' is not used as well as BAM not being used?

-Is the main issue that you are not able to find a way to accept this data due to the fact it's being ignored?