The board is designed to run the little low current plug in driver boards. It's not designed to drive an opto isolated external stepper controller (which is what I suspect you are trying to use).
Just in case I'm guessing wrong:
1) What sort of motors are you trying to run (NEMA 34?, 12A?, 0.25 ohm?)
2) What sort of controller are you looking at (or do you have?)
3) Are you trying to drive a big motor off of the X3 directly?
Just in case I'm guessing wrong:
1) What sort of motors are you trying to run (NEMA 34?, 12A?, 0.25 ohm?)
2) What sort of controller are you looking at (or do you have?)
3) Are you trying to drive a big motor off of the X3 directly?