Bipolar motors have 4 wires (2 pairs), Unipolar motors typically have 6. Some other motors have 5, or 8, or whatever. 8 wire motors are usually wired as 2 sets of bipolar windings (i.e. essentially 2 bipolars wired together).

Bipolar motors (4 wire) or 8 wire stepper motors (that you can therefore wire the phases in parallel to effectively make them a bipolar) are preferred over unipolar motors. This is because bipolars will have lower coil impedance and therefore more power transfer and torque.

Five (5) wire motors are usually in a "star" configuration that has a common ground and require a specialized driver. TinyG cannot drive 5 wire steppers.

Wire pairs are often color coded by convention. Common wire pairings are:

Green goes with Black. Yellow is often used for the center tap of the Green/Black pair in a unipolar motor
Red goes with Blue. White is often used for the center tap of the Red/Blue pair in a unipolar motor
E.g:

Color | Bipolar | Unipolar | Notes
---------|--------------|---------------|--------
Green | Winding A1 | Winding A1 |
Yellow | (none) | Center tap A |
Black | Winding A2 | Winding A2 |
Red | Winding B1 | Winding B1 |
White | (none) | Center tap B |
Blue | Winding B2 | Winding B2 |

Use your volt meter to verify that green and black connect together, and red and blue connect together, and that they don't connect to the other pair. Typical DC resistance across a winding is about 1 to 5 ohms. If you have a Unipolar motor you can just leave the center taps disconnected.


Finding pairs in a unipolar motor is a bit more complicated, but not much. You want to find the outer taps of each coil. These are often color coded by convention (as above). Using a voltmeter to find the resistance across the outer pair. The resistance between the center tap an an outer tap will be 1/2 the resistance between the outer taps.


See more:https://www.oyostepper.com/