Touch probe woe's

[m_c]

That probe shouldn't need any inverting.

As it stands, the G540 input pin must float/be pulled high (I couldn't find the exact details from a quick scan over the gecko site).
Having the probe pull that input to 5V should be fine, as even if it's not opto-isolated a PP should be 5V tolerant.
The probe will then simple switch it to ground when activated.

[Smokie555]

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