Hello folks, I've recently converted a mill with newer electronics. I'm using a PMDX 126 board and the Ethernet SS . Everything works fine..except for the Omron proximity switches. These are the NPN NO types. 10 to 30 volts, 100mA. The issue is if I install just one switch..everything works fine. I move a piece of metal over the switch and the diagnostic input screen blinks yellow. When I install a second switch in parrallel the diagnostic input stays yellow.  I've tried all the switches by them selves and they all work... 

Is this old man missing something ? Do i need to use resistors ?

Any help will be greatly appreciated 

pete

Problem solved   I read some where about using diodes and gave it a try ..it worked. The diodes used where 1N4148.  I installed the diodes in series with the black leads on the proximity sensor. The cathode towards the sensor and the anode towards the pin on the breakout.

A diagram is always nice to have! wink wink!