have obtained a quantity of nice NPN inductive sensors which I am using with the C11 board. Each sensor has a small indicator LED which lights up whenever a metallic object is within range. Lets call this the indicator.
If I connect the sensor to the +12v supply the indicator lights up whenever a metallic object is within range (approx 2mm) so far so good, they seem to work.
I'm usind two sensors wired in parallell as in the diagram attached. One will be at each end of my screws and act as linmit switches. One end will double up as the home switch.
The sensors are using an independant 12dc supply. the ground of the supply is connected to the ground of the C11 board. When I connect the output of the sensor to the input of the C11 the indicator LED lights up. It cahnges brightness when a metallic object is in range and the C11 board detects the change also. When the change is detected Mach3 does exactly as it should.
The Led on the C11 board switches on and off as it should.
OK this seems fine EXCEPT that
If I disconnect the sensors at the point marked X on the sketch then there is no difference at all in the way things are working as described above. The 12v from my external supply goes to the C11 input via a 4.7k resistor as shown. The negative of my supply for the sensors is connected to the C11 board.
This is most puzling, and lends me to believe the sensors are wrong.
Can anone help me wire these correctly ?
Many thanks
George