[Cecil]

Are you by any chance using Jaguars? You could always wire your limit switch directly to the inputs on the Jaguar itself and let it do all the work.

On the other hand, how is your limit switch wired? Remember that the Digital Sidecar inputs are always pulled high until you pull them low. Wire your limit switch with the signal wire going to COM and the negative wire to the NO terminal.

With this wiring, you will also need to switch your comparison values (switch the 0 and 1) so that when the switch is pressed (goes false) it will stop your motors