2. Four-lead bipolar stepper motors

The diagram below shows a standard four-lead bipolar stepper motor. To control this motor with the driver, connect stepper leads A and C to one pair of motor driver outputs on the board and stepper leads B and D to the other pair of driver outputs. Note that if you happen to swap which way the wires are connected for any coil, the stepper motor will turn in the opposite direction, and if you happen to pair up wires from different coils, the motor should be noticeably erratic when you try to step it, if it even moves at all.