To begin, if your stepper motor only has four wires, this means it can only be used with a bipolar driver. You will notice each of the two phase windings has a pair of wires, use your meter to identify the wires.
4 Wire Stepper Motors
W numerous motors make the most of 6- and 8-wire configurations, the majority of bipolar (1 winding per phase) stepper motors offer 4 wires to connect towards the motor windings. A fundamental 4-wire stepper motor is shown in Figure 1. Connecting this motor kind is extremely simple and merely demands connecting the A and A' results in the corresponding phase outputs in your motor drive.
There's not a lot detailing right here. The 4 wire stepper denotes a single feasible configuration and that's of a bipolar stepper motor. We don't have to bore us with particulars like whether or not this motor is variably reluctance, permanent magnet or hybrid as that only relates to building. What we have to understand is the fact that two wires are for PHASE A and also the other two wires are for PHASE B. Which 1 is PHASE A and which 1 is PHASE B is type of arbitrary.
If you have the motor datasheet then you know which wires represent which. But if you do not have this document, just do a quick continuity test and determine which two wires are connected together through an inductor. You can also use a simple BACK EMF test in which you short two leads together. If it is harder to move the rotor, then those two wires form one of the phases. If the rotor moves as easy as with no wires crossed over, then those two wires are not connected through a winding. Keep on going until you find both phases.
The Five Wire Stepper
This motor is also equally easy to deal with as it can only be wired as an unipolar stepper motor. There is really no way to use this motor in a bipolar configuration as all the center taps have been shorted together. Do note this motor style is quite rare. I think these motors were more common a few years ago when unipolar motors were much more cost effective. Today, however, since driving bipolar motors is not a superbly expensive endeavor, the five wire stepper motor is not as common as it used to be. Instead, the six wire stepper motor has replaced the five wire stepper motor because of what we will see next. If you do happen to get your hands on a five wire stepper motor, here is how you wire it:
The Six Wire Stepper
We can now start to complicate things. As it turns out, the six wire stepper is optimized to operate as a unipolar stepper motor but it is rather doable to use it as a bipolar stepper motor as well. The trick, however, is that there are multiple ways of wiring the motor as bipolar and it all depends on what you will want to achieve. For example, do you want speed, or do you want torque? Maybe you want both? Well, I can only promise one or the other by utilizing conventional drive technology. If you want both (torque and speed) you will need to resort to some highly advanced drive technology, which although available out there, is not in the$5.00 range.
So lets first see how to wire the six wire stepper as a unipolar motor:
A bipolar driver will require you use only one end wire and one center tap of each winding. With a five wire stepper motor the wire setup is very similar to the six wire driver, the main difference being the center taps are connected together internally, bringing it out as one wire. This will make the motor only function as a unipolar driver. Also, the windings will be impossible to identify without trial and error, the best you can do is try to identify the center tap wire since it has half the resistance.
Finally there is the eight wire stepper motor, which is much like the six wire. The difference being that the two phases are split into two separate windings. When this is done it allows for the stepper motor to be connected as a unipolar motor, as well as three different bipolar combinations.
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