Stepper Motor wiring

Also:

• Javascript page to find the center and phases for 5 and 6 wire unipolar stepper motors from your resistance measurements between the wires.
• NEW! Roman Black's Linistep 1. stepper controller kit Proceeds support PICList.com

Rodney McLatchy says: "...attach A+ and A- to 2 probes of the scope common to ground, and spin the shaft by hand. On the screen they should come out 180degee. out of phase. If one phase is backwards they would look the same. Or if I mixed an A with a B, 90degees out."

matejbinclKILLspam at hotmail.com asks:

/techref/io/steppers.htm Hello i have the stepp motor number IBM P/N 1325059,
and another number 23LQ-C302-G1V, MINEBEA CO:., LTD
and i want to knew which wire is for + and - and remote?
and how many voltage can i put on at:::?

James Newton replies: For most common 5-wire unipolar motors;

• find common "centre tap" using an ohmmeter the resistance between the center and any leg of that coil is 1/2 that from leg to leg. Measuring from one coil to the other will show an open circuit, since the 2 coils are not connected.
• common goes to M+ power
• other 4 wires are the phases

With 6-wire unipolar motors;

• find the 2 common wires
• connect these together
• connect commons to M+ power
• other 4 wires are the phases

Hook up the controller A+, A-, B+, and B- terminals to the phase leads (guess at the phases) and try to step slowly.

If the motor does not turn, try swapping one A wire with one B wire, you may have connected the motor phasing wrong. If you have the phasing wrong, the motor will tend to sit there and "wobble" or "buzz".

If the motor turns, but in the wrong direction, you only need to swap the two A wires with each other.

+

Another way to figure out which wire is which for a motor without using a meter:

First, arrange the wires so that there is no way for any of them to be contacting another.

Pick the first wire, tape it and label it "A"

Steve Baldwin says: I have quite a collection of steppers and in most cases the difference in detent torque with a coil shorted or not, is quite noticeable. However, in one case, it wasn't. That was with an old 5" floppy drive motor. Probably the one most likely to be found surplus.

Spin the motor and notice how hard it turns, then connect "A" to one of the other wires, and spin the motor again.

• If you don't feel any difference, put that wire back and try another
• If it feels harder to turn, label that wire "A" just like the first wire, put it back, and go on.

When you have all the "A" wires, pick up another unlabelled wire and label it "B" then repeat the spin test until you have all the "B" wires.

Repeat with C, D, and so on until you have all the wires in groups.

8 wire motors: If you only have two wires in each set and you have 4 sets (8 wires total) you can just pick one "A" wire, one "B" wire, one "C" wire and one "D" wire and hook them all together. This is now your common or M+ wire and the other wires are the phases. This wiring causes the motor to behave as a unipolar motor. It could also be wired together in a bipolar configuration if that were desired. Some Bipolar drivers accept 8 leads, but many take 6 leads. In that case, one wire from each of two coils forms one common and one wire from each of the other two coils forms another common which results in the same wiring as a 6 wire motor.

6 wire motors: If you have two sets of 3 wires (a 6 wire motor) you need to find the center wire of each set.  Starting with the "A" set, label the wires A1, A2, and A3 in any order. Connect A1 to A2. Feel how hard it is to spin. Now connect that same A1 wire to the A3 wire in the set.

• If it is easier to spin, then the A2 wire is the center. Re-label A2 as "AC"
• If it is harder to spin, then the A3 wire is the center. Re-label A3 as "AC"
• If it is the same, then the A1 wire is the center. Re-label A1 as "AC"

Repeat this for the B set to find the B center wire "BC"

Connect AC and BC together to form your common M+ wire. This modifies the motor to become a unipolar stepper.

5 Wire Motors: If you have only one set of 5 wires then you have a standard unipolar motor. Connecting ANY two of the five wires together causes the shaft to be a little harder to turn. You might have noticed that one of the wires caused the motor to be harder to turn than the others. That was the center wire. If all the connections seemed about the same, the first wire you picked was probably the center.

Once you know which wire (s) is(are) the common, you can find the order of the phases with a stepper controller or a battery. If you can connect it to a controller and provide direction and step signals continuously, the motor will either turn, or shake. If it shakes, swap one of the A wires with one of the B wires. If it turns in the wrong direction, swap the two A wires. If your wires are labeled A, B, C, D rather than A+, A-, B+, B-, that should read: If the motor steps back and forth, swap B & C. If it runs backwards, swap A & B. {Thanks to Steve Baldmin or TLA Microsystems Ltd, Auckland, New Zealand}

With a battery, connect the common to one side, Then touch each wire to the other side of the battery until you find one that spins clockwise. Call this A. Pick another wire. If it goes clockwise too, call it B, and so on. If it doesn't, re-apply A, then pick another wire. Eventually you get A,B,C & D, and it should spin clockwise when voltage is applied in sequence. Reverse the sequence, and the motor should go backwards. {Ed:thanks to Tony Smith}

Bill Krause says:

I use a sure-fire technique for identifying two-phase stepper motor wiring (5,6,8 wire) including the order of the phases that requires only a d-cell battery, or a battery plus an ohmmeter. This works because if you excite a portion of one winding (from center-tap to one end ("phase") of a phase winding on a 5 or 6 wire motor, or one of the half-windings on an 8-wire motor) AND excite equally AND IN THE OPPOSITE POLARITY the other portion of that same winding (from center tap to the other end ("phase") of the same winding in a 5 or 6 wire motor, or the other half-winding associated with the same phase on an 8-wire motor) the motor will turn freely because the net excitation to the stator is zero. This situation will only occur when you are exciting two half-windings of the SAME PHASE in this manner. Therefore using this method you can sort out center-taps, associated half-windings, winding polarities, and phase association in the motor.

(In case you're wondering; when you short the two outside ends of a winding in a 5 or 6 wire motor and then apply excitation (the battery) across the center-tap and the shorted ends, you are applying excitation to the half-windings in parallel, OPPOSED POLARITY. If you draw a schematic of the hookup this becomes evident.)

Here are examples for 6 and 8 wire motors (I'll use the battery+ohmmeter method, because any old ohmmeter will work and almost everybody has one)

6 Wire Motors: With the ohmmeter, separate the wires into two groups of three (there'll be continuity among the three in a group, but no continuity between the groups) {ed: or use the method above to find the groups without a meter}

As you are testing, make sure that none of the motor wires are shorted together, other than the ones specified in the test.

Arbitrarily label the wires in one set a, b, and c.

Twist together a and c and hold them to one side of the battery while holding b to the other side. Does the motor turn easily?

• If yes, then b is the center and a and c are the ends.
• If not, then try again:

Twist together leads b and c and connect them to one side of the battery and lead a to the other. Motor turn easily?

• If yes, then a is the center and b and c are the ends.
• If not, then try again:

Twist together leads a and b and connect them to one side of the battery and c to the other. Motor turn easily?

• If yes, then c is the center and a and b are the ends.
• If no, then there’s an unknown problem because those are the only combinations.

Repeat the labelling and test sequence for the other set of wires.

8 Wire: Take your ohmmeter and find the pairs of leads that have continuity between them and those four pairs are the two windings (each split in half). Just to make sure you don’t get snookered, measure between one wire of one winding and one wire of all the other windings and make sure you don’t have continuity there. Label the four pairs of leads: a, b; c,d; e,f; g,h.{ed: or use the method above to find the groups without a meter}

Make sure none of the motor wires are shorted together.

Turn the motor shaft and note how difficult (or easy) it is to turn.

Hold wires a and b to the ends of the battery. Note how hard the shaft turns (it should turn a lot harder than before).

Twist lead a to c and lead b to d. Hold leads to battery. Does the shaft turn as easily as when no power was applied?

• If yes, then you have found the two halves of one of the windings and you have them connected parallel-opposing.
  You can now label the leads: a=1, b=2,d=3,c=4.
• If no, then try again:

Twist a to d and b to c. Connect battery. Rotate easily?

• If yes, then a=1,b=2,c=3,d=4.
• If no, then try again:

Twist a to e and b to f. Connect battery. Rotate easily?

• If yes, then a=1, b=2,f=3,e=4.
• If no, then try again:

Twist a to f and b to e. Connect battery. Rotate easily?

• If yes, then a=1,b=2,e=3,f=4.
• If no, then try again:

Twist a to g and b to h. Connect battery. Rotate easily?

• If yes, then a=1,b=2,h=3,g=4.
• If no, then

Twist a to h and b to g. Connect battery. Rotate easily?

• If yes, then a=1, b=2,g=3,h=4.
• If no, then there has been an error, because those are all the combinations.

At this point let’s say you have successfully identified leads 1,2,3,4. Now to identify leads 5,6,7,8. Put leads 1,2,3,4 out of the way, but make sure they are not shorted together. Relabel the remaining leads as a,b,c,d.

Repeat the part of the testing above that involves a,b,c,d, but use lead numbers 5,6,7,8 for your results instead of 1,2,3,4.

These tests are sure-fire and work every time. Hope this helps

Questions:

• ryanKILLspam at ylamericanwebinc.com asks:

  I have an older animatics 4 axis unipolar stepper controller and I would like to connect an 8 wire 2 phase Vexta stepper motor to it. The controller has output leads numbered 1-8 with no markings of A,-A,B,-B. Is there any way of testing the driver output leads to know which 8 leads of the motor (A,-A, A,-A, B,-B, B,-B) to connect to the driver leads 1-8?

  James Newton replies: The only idea that comes to mind is to fire up the controller with a set of resistors connected from each output to ground. Then measure what the outputs do after each step pulse is applied. What resistor value to use? I have no idea.+

  +

• yarr86KILLspam at hotmail.com asks:

  hello:
  i bought a steper motor from farnell comp they didn't give us data sheet for the steppr ,the stepper has 6 leads ,driver also comes with the stepper i need to knw how can connect these pins to the driver,the driver take only 4 leads but what bout the other two,are they gruonded or what?plz help me

  James Newton replies: Notice from the pictures at the top of this page that a 6 wire unipolar motor looks just like a 4 wire bipolar motor if you simply ignore (do not connect) the "common" leads (A and B in the pictures) and instead connect only A-, A+, B-, and B+. Figuring out which lead is which is what the rest of the page is all about.+

  +

• jbinikosKILLspam at dslextreme.com asks:

  I have 4 axis Micro Step Motor drive with coil markings A,-A,B,-B. The 8 wire Stepper Motor has markings for Bi-Polar A,-A,-C,
  C,B,-B,-D,D. How do I connect the 8 motor wires to the 4 post of the Driver Board ??

  +
• arteezanKILLspam at gmail.com asks: " is it possible to control the stepper motor without using any ICs but using only pushbuttons and the voltage?" James Newton replies: Sure, and it is also possible to build a computer out of paper clips and flashlights, but why on earth would you want to?+

  +

• michaelhKILLspam at iae.nl asks:

  http://www.qsl.net/pe1rok It seems to me that the coils are labelled correctly, but placed wrong. A1 and A2 are each other's opposite instead of neighbors. On the 'steppers.htm' page it is right. On this page (wires.htm) it is not drawn right.
  The recipe to identify the wires is helpful. I may add that identifying wires with six (or 5-wire) motors the ohmmeter method is the easiest. Who really cares about the sequence. If it is not right, swap a1 and a2, or b1 and b2.

  James Newton replies: Yes, they were wrong, thank you for pointing that out. I've corrected them now, please let me know if these are again correct. +

  +

• proto_nKILLspam at yahoo.com asks: " How to connect an old 6 wire / 3 independent coils bipolar stepper?" James Newton replies: Are you sure it has three independent coils? I'll bet it has 4 coils, two commons (one for each set of two coils) and 4 single coil wires. See the pictures above.

  If it really has three coils, I would guess it needs a special driver that produces 3 phases rather than the more common 4.

  proto_nKILLspam at yahoo.com responds:

  To James Newton: My stepper (an old one, from Robotron printer) is a bipolar one because each coil must be separately powered to obtain (from each) a step and, after this sequence, I must reverse the polarity for each of them and maintain their order for the continuity of displacement (sense).
  I suppose, a triplet of H bridges must be the partial simplest solution.

  .