1756-hsc

I'm using a 1756-HSC counting Pulses from BEI encoder. I get the counts back and in the right direction as expected. Once every so often (happened twice yesterday, couple of time today) the counts just take off. Yesterday it took off negative, this morning the counts took off positive. The line drive light for the correct direction does light up, but the motor never moves. Using shielded/grounded cable. Does not happen on the other 3 that I have hooked up in the same program. Anyone have any ideas?

TIA
Worm

It could be induced noise. I have seen it before. The 1756-HSC should pick up the pulses coming in out of phase or too quickly and generate and error. Apparently it worked in your case because the motor didn't move which is good. Does the 1756-HSC report errors? If so I would check to see which errors were generated. I seriously doubt this is a HSC problem.

It is time to check wiring and get a scope.