Z Touch-off Puck
From PROBOTIX :: wiki
Retrofiting an existing machine:
Here is the inside of the connector for machines without the ATLaS Tool Length Sensor:
In order to use both the touch-off puck and the tool length sensors, you will need to cut off the existing DB25 connector for the tool length sensor and wire it in to the DB25 connector for the touch-off puck, as seen here:
After installing the puck, you will need to reconfigure the software to recognize it: LinuxCNC Configurator
Z-puck Usage
To set the Z origin using the z-puck, attached the aligator clip to the tool by either clipping it, or using the magnet. Its a good idea to touch the puck to the tool and watch the [PROBE] indicator on the screen to make sure the software is recognizing the probe. After the initial configuration, it should always function, but it never hurts to check in the event the puck was disconnected, broken wire, etc. If the puck is not functioning, the probe operation will most likely break your end mill.
Place the puck under the tool, then click the [Set Z Origin w/ Puck] button. Be careful to keep your fingers out of the way. The Z-axis will probe down at 10IPM until contact with the puck is made. At that point, the Z origin for the height of the puck will be subtracted from the Z height, and current coordinate system Z origin will be set to zero at the base of the puck.
Click here to learn about the new Axis interface: NEW_LinuxCNC_Configuration#Axis_Rev1.5_Interface