Thanks for the help m_c and I hope I can follow this.

My Gecko input pin currently reads 12v, when I earth this pin to the Gecko it triggers Mach3’s LED correctly for my touch plate, so do I connect the touch probe output to the 12v input pin? And does the touch probe need to be on the same power supply as the Gecko for a common earth?

Sorry if I sound a bit dumb but I’m better with the mechical stuff

Cheers
Ross