SAE J 1939

Masia Jean-Baptiste 8 years ago in IQANdesign updated by Ulrik Zakariasson (Software development) 7 years ago 2

On a original Tigercat vehicule Image 111 ,

We can find :one MD3 ,one XA2 , one XS2. The Md3 send (TSC1 : SAE J 1939 frame) and receive SAE J1939 from the ECU.
see the original drawing:

Image 112

My custumer want to add one MD3 and one MC2 in the tigercat to drive one other accessories
my system:
Image 113
My VIN must accelerate the engine and my proportionnal outputs. ( automotive system )

We would to like a new MD3 ( MD3(2) ) send a TSC1 (SAE J 1936 frame) and the old MD3 receive SAE J 1939 frame CAN . We have affraid that the engine received 2 TSC1 message and the engine stop !!! ( conflict !!!!!! )
Image 114

I don't have the original program of the vehicule (picture (1) MD3, XA2, XS2).
Do you have a solution for stop the TSC1 transmission on the original MD3 or other solution?

Please feel free to contact me if you have any questions .
If you send out TSC1 with the same priority and source address, you will undoubtedly get a CAN arbitration error. One of the CAN controllers will quickly go into bus-off, and that MD3 will show a CAN error.

If you send TSC1 with different priority and same source address, then CAN in itself will not be the reason for failure. But the engine would receive conflicting messages from what it would believe is the same controller.

If you send TSC1 from different source addresses, then it depends on the engine which source address it is that will win, if it does not see this as an error. Most engines only accept TSC1 from a few limited source addresses.

Obviously, if your add-on goes in and overrides the original system, then the machine may not work as designed.
What I suggest you do is to speak to the OEM about this modification, we should be able to provide you with a contact person.