Maybe OT: High-Speed Headaches!

[dcooper33]

Thanks Okie for the link. Good reading. I think I will go back on this machine and insulate the prox mount and bolts from the machine structure, as insurance against trouble down the line.
For the next one, I will go with shielded cable and a line filter from the beginning, hopefully save my sanity a bit!

The really nutty thing is that I had a Fluke dual channel scope hooked up to the prox feedback when running off the Sola 2.5amp at one point. The pulses I was seeing looked to all be of equal amplitude, duration, and frequency. There was a little sawtooth on the top of the square wave, but it didn't look to be of any consequence. The overall shape was very square.
After seeing this, I was suspecting card issues on the plc, but then the erratic counts went away with the AB PS. I never got a chance to look at the waveform on the signal with the AB PS, but I may do this tomorrow, just for giggles.

 

[Lancie1]

There was a little sawtooth on the top of the square wave, but it didn't look to be of any consequence.

In most cases it probably would not be of any consequence. But when bumping against the limit of switching speed for the total system (prox switch speed, PLC input switching speed, PLC scan time), it very well might be the differecne between accurate counts, or not.