CAN testing

[Yves]

Is there a way to test CAN on the ms3X ?

[racingmini_mtl]

I'm curious to see what others will suggest. The only way I can think of are either through the use of a CAN sniffer or with an oscilloscope. With the oscilloscope, you could see if the issue is the CPU, the CAN transceiver, the board or the connectors because you can scope both sides of the CAN transceiver and anywhere along the signal path.

One thing to check are the solder joints on the 40-pin socket on the main board corresponding to the CAN bus (pins 6 and 11) as well as the 40-pin headers on the MS3 card.

Jean

[jsmcortina]

What Jean said. As I have multiple Megasquirt ECUs on my bench, I just hook up to another one and test CAN passthrough.

James

[Yves]

I have neither of those.

[jsmcortina]

Probably out of luck then!

What exactly are you trying to test and why? Is there a fault or you are doing it for fun or?

James

[racingmini_mtl]

He has problems with CAN bus comm with an IOx. He was no longer able to have comm between the MS3 and the IOx after being fine initially. I tried to diagnose the issue remotely but nothing was working after checking with different firmware releases, checking continuity between the 2 devices, checking with TS and the port scanner.

He has returned the IOx to me and it is working fine here. So the issue is somewhere in the MS3 or the wiring. The continuity tests should eliminate the wiring loom and the connector so what is left should be one of the following: the main board, the 40-pin connectors, the MS3 board, the transceiver or the CPU.

So to test everything would require an oscilloscope: the boards and connectors could be checked with a simple meter but the transceiver and CPU would need a scope. Unless someone knows of a way to do some tests with a simple meter. And at this time I still have the IOx (which I'll return as soon as possible) so that also makes testing harder for him.

Jean

[Yves]

Want to add the following : I also checked resistance. I remember it being 69 ohm on both sides. If I'm not mistaken this should be in between 50 and 70 (based on what I read on the inet)