DIO on the Digital Sidecar
 

I'm investigating different optical sensors for detecting frisbees, and I'm curious if I'm reading this right.

I'm looking at the switches I have handy, and I'm trying to understand the NPN and PNP terminology.

I'm used to the idea of shorting signal to ground for one state, and opening them for the other. So PNP and NPN are a little different from what I'm used to.

So please tell me if this is correct:
NPN - Signal (Q for sick sensors) is normally at your source/load/input voltage - 12V. When made, it connects the signal to ground.

PNP - Output pulls up to the supply - 12V. So it's normally signal shorted to ground. When made, it pulls the signal up to your source voltage.

Am I correct? Will the DIO have any problems with seeing a signal of 12V and 0, rather than 0 and 5? Along those lines - what does the change need to be between signal on and off for the DIO to see it? 1V? 2V? 5?

Re: DIO on the Digital Sidecar
 

NPN outputs are typically "floating" when off. They don't source any voltage. All they can do is set the output to ground when they're on. So they're perfect for connecting to a Digital Sidecar, which supplies a pullup resistor to 5v on the digital input pins.