The digital ports available on the NI motion boards are generally designed for static digital I/O operations i.e. low speed. An example of this might be the periodic checking of the state (Low/High) of a mechanical switch input. You mention that you need to get these inputs really quickly - could you define "really quickly" in terms of readings/second?
The software approach for reading these ports is simply to call the appropriate function/VI and the rate at which you could perform this operation in a loop will be dependent on the other activities going on in your application, speed of PC etc. A simple application that only reads the digital port in a loop could give you a maximum reading rate, but you will need to understand that other bits of your applicatio
n will have an impact on the reading rate.
There are a number of trigger inputs available on the 7344 motion control board. Depending on the nature/use of the switches you are referring to, it may be possible to consider using other functionality on the board to help your application. I would be happy to help by offering advice if you could provide a bit more information about the scope of the application you are developing.
Jeremy
