[Customer question]
Is it possible to have the PV750 require a USB stick with a certain file before it carries out a certain function?

This would kind of depend on the function you want to implement. But you could write a script that checks for the existence of a file on the USB stick periodically (say every 1 to 5 seconds). If it sees the file, then it could fire an event, or read the file for instruction, etc. Would be up to you at that point.