I'm having an electronics problem and I'm hoping someone can help. I ordered three of these optical switches : http://search.digikey.com/scripts/Dk...ds=365-1234-nd to use as spindle index pulse and two home switches. Data sheet here: http://www.optekinc.com/datasheets/OPB930-940-L&W.PDF
I got OPB941 buffered open collector (top right page 2 of data sheet). To test I wired from 5VDC to LED (w/ resistor) to "output". I thought with the slot unblocked the output transistor would be on and LED would be lit. Turns out the opposite is true. Slot unblocked = LED off, Slot blocked = LED on.
For the spindle pulse this is fine but for the home switches I want the "normally closed" logic so if I have a broken wire I don't crash. I can just order the inverted open collector but I'm curious how the circuit actually works. Obviously I'm misreading the diagram.