Stepper motors may come with four, five, six or eight wires. This article will help you identify the correct way to wire an unknown stepper motor.
If your stepper motor has four wires, it can only be used with a bipolar driver. Each of the two phase windings has a pair of wires. Use your meter to identify the pairs of wires with continuity between them and connect them to your stepper driver.
A six wire stepper motor has a pair of wires for each winding like the four wire motor, but it also has a center-tap for each winding. It can be wired as either unipolar or bipolar. Use a meter to divide the wires into sets of three wires that have continuity to each other. Then identify the center taps. The resistance from the center tap to one of the end wires is half of the resistance between the end wires. To connect to a unipolar driver, use all six wires. For a bipolar driver, use only one end wire and one center tap of each winding. You can also use the full winding in bipolar mode at half the rated current, but the high speed torque will be reduced because it has four times the inductance of the half-winding configuration.
A five wire stepper motor is like the six wire motor but the center taps are connected together internally and brought out as one wire. This makes the motor impossible to use with a bipolar driver. It also makes the windings impossible to identify without trial and error. The best you can hope to do is identify the center tap wire because it has half the resistance to any other wire.
An eight wire stepper motor is similar to a six wire motor, except that each of the two phases is split into two separate windings. This allows the stepper to be connected as a unipolar motor as well as three different bipolar combinations. In addition to the bipolar half and full winding modes, you can also connect the two halves of each phase in parallel. You will probably need to consult the motor’s data sheet for this one in order to get each half winding properly phased with the other.