bought a Centroid KP-1 touch probe, Mach 4 not detecting probe trip.  Using ESS and C82 board with Machh4.  White wire from probe to Port 2 pin 9, active low, Black wire to Common. Green wire to ground and red to +24 volts DC. I hooked a volt ohm meter from pin 9 to common and the meter indicates pin goes to common when probe tripped. Probe goes from Greed LED to Red when tripped and verified with meter.  Mach shows no change of state. Diagnostic Page probe LED does not change. Probe enabled set to port 2 pin 9 active low. selected probe 0 in Mach4.  Any help would be great.

From what you are saying, I see that you are connecting this to the terminals of the C82.  Keep in mind that the inputs of the C82 use bidirectional optos that work from +5vdc to +24vdc.  Maybe you are not wiring the correct common for the signals.  I think that the output of the centroid probe is equivalent to an NPN, and this wiring diagram may help:
https://www.cnc4pc.com/knowledge/article/195

You can also open a ticket in our website and send pictures of your wiring and we will give you a hand with this: https://www.cnc4pc.com/helpdesk/customer-care-4?contact_form=1

Arturo Duncan
https://cnc4pc.com