Wondering if you ever figured this out. I am having a hard time getting the g540/Mach3 and simple touch probe to work without having intermittent "digitize" light flashing.
The digitize light does work normally to show the connection when I have it wired as you describe in option #1 (plate on bed, and clip on end mill, connected pin 13 and -v com). But then it also flashes randomly when the two points are not touching.
I'm using shielded wires with the drain going to a common ground on the electronics box end. Tried jacking up the debounce just to see if it works. Made sure that the continuity and wiring was all ok. Tried another open pin. No luck.
The same wiring style/type is being used for my home switches with no issues whatsoever.
Any help would be MUCH appreciated.
Scott