So I've bought these http://www.ebay.com.au/itm/5Pcs-PNP-...72.m2749.l2649
I thought they were pretty simple PNP senor. My Parallel Port Break Out Board (BOB) calls for a ground input on the input pins. So ve+ and Gnd to brown and blue then black to the BOB. I was a bit worried to start with because when I put my meter from ve+ to the black wire, I got 300mv when not tripped and 12v when tripped. Obviously showing a ground leak and getting 300mv when not tripped. I thought it might show as being tripped all the time. Unfortunately, it doesn't show tripped at all.
So this is what I have:
Senor tripped. I get 12v between ground supplied by the sensor and ve+. (thought that proved ground on the wire from the sensor)
Hook that same wire from the senor to the BOB and nothing is seen. (something is wrong)
Use a jumper wire directly from ground to the BOB (proves the BOB is working correctly and can see ground)
I know someone is going to suggest using a relay but I don't think it should be necessary and the delay for a mechanical relay to trip may affect home accuracy.
Thanks in advance to whatever advice is given.
Happy Days