The output voltage from the probe seems to match the input voltage so it can be 5v to 24v. I opened my CNC control box today to try the probe output and earth idea but had forgot my Gecko power supply is 48v which complacated things again. I did try dropping the voltage to the probe to 12v with a buck convertor inline with the 48v supply but no joy.

I’m just doing something wrong and as John Haine says his works great.

I just need to get this probe output that drops to less than 1v when triggered to earth the gecko pin but my Mosfet setup didn’t work on the machine. Can you give me a guide on this NPN transistor setup as it sounds like the answer. Thank again for the great advice.