J1939 mode 2c dynamically define pid ?

[04colyZQ8]

Is there such a thing as mode 2c like the j1979 mode to dynamically define pid, available for the j1939 can protocol?

If so does anyone have an example of how to define it?

[04colyZQ8]

Should be possible with dm14 dm15 dm16 after unlock with seed key using dm18.
Idk what dm is? Or how to send

[antus]

Does this post here help you? Mode 2C looks like dpids, and yes they exist for can as well, but they are not part of J1938 that I can see. Rather they are still one and the same mode 2C.

viewtopic.php?p=45804#p45804

[04colyZQ8]

Yeah that would work for gm can. But I don’t think it wires for j1939

[04colyZQ8]

I got it to spit out raw hex values from sending a request of direct Ram address.

However it won’t do it if the controller is being used like any inputs going in break the connection? Only seems to work at key on?

[yoda69]

J1939 is pretty clearly defined for many parameters on the CAN network, but there are some manufacturer specific items still available.
As much as J1939 is “defined” not all parameters/messages are available or supported by all manufacturers or required depending on the vehicle.
Typically you don’t need to request PIDs, just listen into the CAN and decode.
What exactly are you trying to do or messages are you looking for?

[04colyZQ8]

J1939 is pretty clearly defined for many parameters on the CAN network, but there are some manufacturer specific items still available.
As much as J1939 is “defined” not all parameters/messages are available or supported by all manufacturers or required depending on the vehicle.
Typically you don’t need to request PIDs, just listen into the CAN and decode.
What exactly are you trying to do or messages are you looking for?

Exact memory location is needed, I am writing new code, which has been injected into the stock disassembled code. I am using many new ram addressees that have not been defined yet. However I did find a way to dump the entire ram, but it would be handy to watch some of the variables live. I have not found where the stock SPN and PGN messages are implemented, otherwise I could just add my own or highjack one that is close to what I need.