At the MARC competition, we had a very interesting issue. It started out as a momentary “blip” in the can bus during a match. We lost all control of the robot momentarily and the canbus usage as reported by driver station logs dropped to zero.
We could not reproduce the error after the match. A couple matches later, it happened again. This time the ‘blip’ was longer. But again, we couldn’t reproduce it. However, it appeared to happen when we ran our hilo motors (two talon srx’s driving 2 775s with a versa encoder slice in the mix).
The third time I was field-side when it happened, and it was much longer. I got to the robot and noticed that all the speed controller lights were blinking red. This lasted 30-45 seconds.
Back in the pits, we were able to finally reproduce the issue. We noticed a mechanical bind in the hi-lo that appeared to cause the current on the 775’s to spike. When that happened, the can bus would drop. We had already checked all our can wiring, and re-terminated our resistor at the end. We even tried utilizing the resistor in the PD board as well with no change in behavior.
We unplugged the breaker from one of the two hilo 775’s and thought we had the problem solved, as the hilo went up and down (slowly) without killing the bus. Back on the field though, the first time we lifted the hilo, the robot died. It never regained can bus. In the pits afterwards, we were able to duplicate this. Solid flashing red. Unfortunately the last hilo 775 was buried under the hilo itself and could not be switched out quickly, and it was also the one that was connected to the hilo encoder. So it was game over.
Has anyone seen this before, where a single Talon SRX is capable of somehow taking down the can network when it runs?