[Ken Streeter]

Originally Posted by pfreivald

We tried replacing the encoders, the wires from the encoders to the sidecar, the sidecar, the cable from the sidecar to the bumper, and the bumper... Even replacing *ALL* of them yielded the same result.

What kind of encoders are you using, and how are you wiring them? Are you positive that the encoder wiring is correct?

I don't have any magic answers, but can suggest a few things to try...

We use the USDigital encoders exclusively, although different models (generally E4P and E7P) and wire them with the 4-pin USDigital cable going to two separate 3-pin PWM-style connectors, but with each connector only using two conductors. One connector will have "A" and 5V; the other connector will have "B" and GND. With the way that we wire them up, it is essential that the connectors be wired the correct way round, and it is easy to get them wrong. When they are wired incorrectly, wierd sidecar behavior can result.

Another thing to check -- is the ribbon cable from the cRIO module to the Digital Sidecar ok? We had a cable which had been damaged due to a robot accident and had intermittent shorts in a couple of the conductors.

I would also suggest checking the power connections to the digital sidecar very carefully. Replace the circuit breaker if you have any reason to suspect it. Consider temporarily replacing the circuit breaker with a small (10A?) automotive fuse -- if it blows, it will do so completely and finally, making it easy to diagnose the problem.