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:
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).