Hi,
got home, had something to eat, sat down.....and suddenly its the next day....I fell asleep!
As promised:
Close any Gcode that is running. Disable Mach4. Click the Operator Tab and select Edit Screen.
In the Screen Tree Manager double click the topmost item, it will be your profile name, in my example 'ESSMillwx4'.
Click the Events button in the Properties panel and viola there are the major scripts that form Mach, including the PLC
script. Click on the script and it will open in the Zero Brane editor.
Be sure to properly close the editor and save your edits, having one of these scripts open when it should in fact be closed,
ie after you have finished with it will crash Mach.
Craig