Stepper motor wiring EIB Board

[Bob]

Hi All,

I recently bought an EIBBoard for a project. I didn’t buy the stepper motors offered by EMS as I have some on hand. Looking over the Eggbot instructions they don’t give a pin out for the board, they have you wire up the motors based on the colors of the wires on the stepper motor. My motor have different colors of wires so the color scheme in the instructions won’t work for me.

The stepper motors I have are wire AC, BD, meaning Coil 1 is AC, and coil 2 is BD if we look at the connector left to right with the drive shaft facing up. Looking at the schematic for the EIB board, the pin outs are 1B 1A 2A 2B. This suggests to me that I should wire 1 coil of the motor to 1B and 2B, so the outside pins, and the other coil to 1A and 2A or the inner pins. Am I reading the correctly? Am I right that A on my motor goes to 1B, C on my motor goes to 2B (outer to outer) and B on my motor goes to 1A and D on my motor goes to 1B (inner to inner)?

Sorry if this is elemental, I’m a software guy, I can read a schematic to some extent but I’m not yet confident that I understand it well.

Cheers
-Bob

• This topic was modified 2 years, 3 months ago by Bob.

[Windell Oskay]

The first four positions in the terminal block “motor 2” drive one motor — usually the “egg motor” on an EggBot — and the second four positions in the terminal block “motor 1” drive the other motor, usually the “pen motor” on an EggBot.

Within either block of four are two pairs. The first two positions in the block drive one coil, and the second two positions drive the second coil in a motor.

If you aren’t sure how to wire up the motor to begin with, touch two of its four wires together and try to turn the shaft by hand. If touching those two wires together causes the shaft to have more resistance to turning, then those two wires are one pair going to the same coil, and the other two wires are the other pair on that motor. (If it doesn’t cause more resistance, then you have

The polarity does matter. Once you hook up both pairs of wires, try rotating the motor under power. If it doesn’t rotate the direction that you expect, reverse the order of one pair of the wires.

[Bob]

Very good, thank you. So coil pairs are next to each other rather than outer and inner. That makes thing easier. One additional question. What might I expect to happen if my coils are out of phase? Meaning Coil 1 is connected +-, but coil 2 is connected -+? I have the data sheet of the motors but it doesn’t indicate which legs are in phase. I’ve seen some data sheets for motors that have a bar over one leg in each coil which I assumed meant if one was connect to positive the other had to be as well. I know with reversible motors saying one side is positive and the other negative doesn’t make much sense, but I don’t know how else to put it unless one leg is considered “prime” or something like that.

Cheers
-Bob

[Windell Oskay]

It should be fine to reverse one pair if you need to.

[Author]

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