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request messages to Cummins engine

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request messages to Cummins engine

by Owen Senmeis :: Rate this Message:

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Hello,

We are developing some products on ISB4/ISBE engine of Cummins. Could anybody kindly answer my following question on J1939?

Now the message with the PGN = 65257 (Fuel Consumption Liquid) should be requested. We have tried several times and find out that it succeeds only with the following request:

18 EA FF 01 E9 FE 00

That is, the Source Address of the request must be 0x01. Are there any special reasons fot this?

Best Regards.

Senmeis

RE: request messages to Cummins engine

by Bram Kerkhof :: Rate this Message:

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Some parts of this message have been removed. Learn more about Nabble's security policy.

AFAIK, there is no stipulation in J1939 that obliges a CA to respond to a request even if it has the PGN requested available.

The only limitation is that it should respond to a request that is directly addressed to the CA rather than the broadcast address, but I don’t see why it couldn’t be picky on which SA is deserving of the requested PGN and which ones get a NACK instead ;-)

If you have to send from a particular SA, chances are that there already a node with the given address on the network and using the same SA from a different node should be a big no-no. Of course that depends on the details of the actual implementation, and I’ve seen far too many “liberal” implementations of the spec.

cheers,

Bram