This kit will drive a Bi-polar and Uni-polar stepper motor drive using externally supplied 5v levels for stepping and direction. These usually come from software running in a computer operation. The direction and step inputs are opto isolated.Direction: This is controlled by 0-5v's applied.Step: A 5v-0v transition between the pins will step the motor one position. The step direction will be according to the voltage applied to the direction pins.