I was on my scheduled days off when I was contacted by a supervisor with an issue with one of my projects. He claims the jogging bits were hanging up and not resetting, causing issues. The machine ran for months with no issue, so I don't know what caused it because I wasn't on site. I talked him through resetting the bits to the proper state through text, and it was the last I heard of it. I'm back in today, so I got a chance to talk to him and look at the project. He had talked to AD support, and they said the stages could be causing it to hang up. I don't see how that could happen. Here is my logic:
This is a dancer setpoint. The line ramps to a stop before it loses the run signal. The unwind is a standalone unit. It doesn't get the speed from the rewind. So, when it stops, the dancer is usually high or low (depending on the direction the roll is unwinding). I made these stages to jog the unwind to put the dancer at the midpoint when the line stopped. So, it compares the dancer position (PV) to the upper and lower comparative points (setpoint +-20 as uppertest and lowertest) and then decides which way the unwind has to jog. It sets the bits to jog, jogging the unwind in the proper direction, until the bit is reset in the later stage. I don't see how this could have any opportunity to hang up. Am I wrong here?