I have a Ex controller with servos system and wanted to add a probe to it. I had read good things about the kp3 from centroid so I went with that. It turns out that the KP3 is wired differently than the KP1 making it much easier to add to my system. The KP3 has 3 wires, ground, probe, and probe detect. I didn’t want to burn a precious input on probe detect, and avid/centroid provides the same don’t spin the spindle when the probes installed capability by using the probes tool number to prevent the spindle from spinning. This meant I could just use 2 wires, one needed to be connected to an input and the other needed to be connected to ground. This is just what Aux 3 is wired up as. Pin 4 goes to input 7 and pin 3 goes to ground. I bought an m12 connector, wired it to the probe wires (pin 4 white wire, pin 3 black wire, pin 2 red wire (unused)) and plugged it in. Configured the software and everything just worked. The only slightly odd thing is that the air detect icon on the avid screen toggles when the probe is touched 
. It must be spying on input 7.
Glad you got this worked out!
For those that do the KP1, you don’t have to burn an input on “probe detect” It will also work by tool number as well, so you can specify a tool number for your probe, and if you’re on that tool number it will never start the spindle.