Re: Numerical value to CAN D1:D0
Please see here: https://stackoverflow.com/questions/318 … -ack-field
"When a receiving node would like to ACK acknowledge the receipt of a frame, what exactly is it supposed to transmit?
The same frame just with a dominant bit for ACK?"
No, every CAN node controller on the bus will usually listen to a message transferred and will automatically check this frame for correctness (CRC).
And it will usually also acknowledge the message by overwriting the recessive ACK=1 ("send" by the transmitter) with a dominant ACK=0 during message transfer. So there is no second message needed to acknowledge the first one.
That's also why you can't have any CAN bus with just one node, because there is no one else to acknowledge and check its sent frames.
Of course, in some controllers these checks can be deactivated or ignored, but not in the common use case."
So basically in my scenario the engine's computer is either accepting the first message but no more (given the sporadic acceptance viewed through OBD2 PID)
the TX period (time) and / or quantity of frames per second are the issue.