I have the following stepper 35L048B2U in my possesion. I looked through similar questions, but could not find a satisfying answer. My motor have 6wires (would suggest universal), but on the digikey page and on the manufacturer one it tells me Unipolar. I am a bit mixed up here. I also tried to see if two wires (the common) were connected together but with no avail.

Do I have a universal or unipolar stepper?

  • \$\begingroup\$ That Digikey link points to the entire Portescap catalog. Which one do you actually have? \$\endgroup\$
    – Matt Young
    Oct 2, 2013 at 22:06
  • \$\begingroup\$ The accepted answer on the question you linked (mine, incidentally) pretty much is the exact same answer I would give here. Unless you can give more specific information about the motor you have, we can't give you any better help. FWIW, universal motors can work as a unipolar stepper motor without issue, so that may be why it's labeled as such. \$\endgroup\$ Oct 3, 2013 at 9:30
  • \$\begingroup\$ I have edited my post with the exact servo that I have. \$\endgroup\$
    – Hawk_08
    Oct 3, 2013 at 15:31
  • \$\begingroup\$ You shouldn't expect the two commons to be connected together. Rather, you should expect half the resistance from the common to each leg of that coil, as between the two legs of that coil. And you should expect no connection at all between any of the 3 wires of one coil to any of the 3 of the other. \$\endgroup\$ Oct 3, 2013 at 16:20

1 Answer 1


You have a universal stepper: it can be driven in either a unipolar or bipolar stepper configuration. Here is a diagram of the connections for a 6-wire stepper:

6-wire bipolar/unipolar universal stepper has two coils, each with a center tap

You should measure the resistance between each unique pair of wires -- this will be 15 measurements. Put them in a table like this:

     1    2    3    4    5    6
1    X    R12  R13  R14  R15  R16
2    X    X    R23  R24  R25  R26
3    X    X    X    R34  R35  R36
4    X    X    X    X    R45  R46
5    X    X    X    X    X    R56
6    X    X    X    X    X    X

Measure resistance from wire 1 to wire 2, enter that for R12. Measure resistance from wire 1 to wire 3, enter that for R13. ... Measure resistance from wire 2 to wire 3, enter that for R23... until you are done.

You don't need to measure the values in the cells marked X since those values are redundant.

You'll find that there are two center taps on your 6-wire stepper motor, which will have resistance R to the end taps on that coil, and those end taps will have twice the resistance, 2R, to each other. The other coil will have infinite resistance to all 3 wires on the first coil. You will have to test to see what the polarity of the motor is, however.

Useful explanation of 6-wire setup from National Instruments:

If you have six coil wires, then each phase has a center tap wire:

  • The center tap wire should have half the internal resistance of the full phase. The easiest option is to use a multimeter to find the two pairs of wires that have the maximum resistance.

  • Connect each phase to the amplifier, and ignore the polarity (+ / -) for now. You have a 50 percent chance of guessing right. The motor should rotate, and if it is in the opposite direction, then switch either phase A and A- or B and B- (effectively reversing directions).


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