Photoeye's not working-Difference between RoboRIO and Digital Side Card?

[Alan Anderson]

Originally Posted by Al Skierkiewicz

I would not, however, recommend a pull up to 5 volts in parallel with the internal pullup to 3.3 volts. That would tie both supplies together and would draw current dependent on the state of the input as connected.

I doubt 50 microamps between the 3.3v and 5v supplies is something to be worried about. Not knowing the detailed architecture of the supplies makes me less confident about that than I could be, though.