You can control a digital output with a PID, but you need to configure it as a TPO (like PWM). This will cause the point to act like an analog point. You may have to configure the PID output in your strategy using the memory map as “PAC Control does not currently support configuring the output of a PID loop as a TPO on a digital module”. Not sure if that omission has been fixed on later version of PAC Control.
Review the following thread:
Also, a mechanical output module isn’t the best for this application if you will be cycling it a lot.