Quote Originally Posted by JohnHaine View Post
Assuming that it has a standard tip and sleeve jack, the sleeve is probably grounded and the tip is the active input. Easy way to test is to open the diagnostic screen (assuming it's available in the KX3 screen set), and look for the "digitise" light while you ground the probe input - it should go green when touched to ground. Probes / edge finders are easy to make - see here;

https://www.model-engineer.co.uk/alb...47864&p=794324
Just to add - I would hope that in a ready-made machine and controller they would have configured the ports and pins, but in case they haven't, or even if they have, you may need to open config/ports and pins/... and check which pin "digitise" is assigned to and what the logic sense is. I think pin 15 is the "standard", and logic low = probe touching is the easiest to handle since an isolated probe tip touching a grounded workpiece pulls the probe low. Most BoBs should have a pull-up already. Renishaw type probes though have a normally-closed switch that opens on contact, so you would need to set the logic sense to active high. The pictures in my post above are of a rigid 10 mm dia probe for edge finding and a tool height setter which has a spring-loaded isolated carbide button at a known height that is grounded when the tool touches it. My probing routine then takes the tool up to 50 mm above the table surface.