Hello Gents

I have a problem, regarding the wiring of the NPN Normally Open proximity sensors and there seems to be some confusion about this, especially when I refer to the schematic, which the user manual supplies. I will attach two pics of the info, which I have.

The MACH3 manual shows that the settings, must be set as ACTIVE LOW, when using NPN type proximity sensors.

The sensors have 3 wires.

BROWN, BLUE AND BLACK.,

This is a test, which I did this evening:

I connected my 24 V DC power supply to the sensor. BROWN wire to BROWN on sensor and BLUE to BLUE wire on sensor. Measured the voltage there and got 24 V. When I placed a screw driver in front of the sensor, the LED came on. This is all Normal.

A search on YouTube revealed that a resistor was used and attached to the BLACK wire. This wire is the SIGNAL wire and was plugged into the port on the BOB. When the sensor was activated, the voltage dropped to around 0 Volts.

Further Testing:

I placed a RESISTOR between the BLUE and BLACK wires and the voltage was shown as 5,8 V with the SENSOR NOT ACTIVATED. When I activated the resistor, the voltage dropped to 0,7 V. This proves the theory of the video clip on YouTube.

The wiring diagram on the NPN sensor, shows a resistor (load) between the BLACK and BROWN wires. The BLUE wire seems to go to the GND on the BOB (I could be wrong)?

Please look at the two attached pics and look how the AKZ 250`s user manual, shows the wiring for this BOB?

If I put a RESISTOR between the BLUE and BROWN wires, I get 23,6 V and when I activate the sensor, the voltage drops to 0,7 V.

I just want to know the correct way of how to connect these NPN type NORMALLY OPEN sensors to this BOB.

Regards

Craig