We have a plasma cutting machine running Mach3 USB. Our limit switches work well until we turn the plasma torch on. The best fix for plasma/ limit switch interference is supposed to be by using an optocoupler. When using only a limit switch, it was connected to DCM and IN1; successfully switching the IN1 pin from 24 volts to 0 volts. I've used a NOYITO 1-Channel PC817 Optocoupler Isolation Module from Amazon. The input turns the sensing LED on and off as it should. So far, I am using the 2nd connection diagram from the top, yielding 24 volts and 14.9 volts to pin IN1. Am I connecting something wrong, or is the optocoupler not what should be used here? Shouldn't the voltage swing from 24 volts to closer to 0 volts on pin IN1?