CAN error about 30 seconds after reboot

Technical CAN
1

Here’s a good one. We’re having a CAN bus issue. About 30 seconds after powering on, we get CAN errors. We’ve tried isolating a NEO and then, separately, each of two CANCoders. So in one test it’s just the RoboRio, a NEO and the PDH with the terminator switch set to Yes. Tried it again swapping in a CANCoder for the NEO. and again with a new CANCcoder. The same behavior occurs each time. We’ve tried reseating the CAN wires in the RoboRio and we’ve tried both CAN connections on the PDH. We’ve also tried our robot software and a test build that does nothing until we set motor values in Smart Dashboard. Even without setting anything, we get the error.
“Swapping” consisted of disconnecting devices from CAN bus and then using jumpers to go from Rio to device to PDH.

  1. Jumpers are twisted pair.
  2. All firmware is up to date.
  3. Double checked the Rio connections. On the PDH it was happening with our original connection which had the PDH in the middle with the terminator switch off and a 120 ohm resistor at the end of the chain on top of our elevator. Then we cut out those devices by setting the terminator switch to On. Then we disconnected the wire going up the elevator. Then we swapped the wired from the pair farther from the terminator switch to the pair next to the terminator switch.
2

What error are you getting?

3

Didn’t find any specific error codes before we had to vacate the school on Saturday.
Where should we look to find codes? Will they show up in the Riolog?

4

Not sure why it showed up after about 30 seconds but it turned out to be two separate loose connections. We’re good now. Thanks.

5

Have you applied hot glue or any other kind of strain relief to your CAN connections? They have an unfortunate habit of coming undone if not

6

This topic was automatically closed 365 days after the last reply. New replies are no longer allowed.