3 wire proximity switch help

[cropwell]

First of all you will need a 12v DC power supply.

The sensor is designed to work from a supply of 6 to 36v +V (Brown wire). 0V (ground) is connected to the Blue wire and the black wire is the sensor output, which switches to ground when triggered. When not triggered the black wire can be considered as not connected to anything internally in the sensor.

You will need a load resistor connected from 5v on the BoB to the black wire and to the input pin on the BoB. I use 10k ohm, the value is not critical but ideally should not be less than 1k or greater than 47k. The blue wire from the sensor should also be connected to ground on the BoB. The BoB must be supplied with a separate 5v power supply and I do not recommend using USB from the computer. This type of sensor acts as a switch between the black and blue wires. I have found that though rated 6-36v they do not work reliably below 10v.

Mach3 sees the input as triggered when it is at 0v.