View Full Version : Need help to connect motor to controller

11-01-2003, 12:45 AM
Hello all,
I need help to connect motors to my stepper motor control. The motor I have is Powermax II Model: M22NSXB-JDS-NS-02 and the stepper motor controller is Stepper3 ROC from stepper3.com. I am new to cnc stuff some please help me how to connect them together.

11-01-2003, 10:31 AM

11-01-2003, 01:05 PM
I have no experience with that board, but the manual (http://www.stepper3.com/manuals/stepper3manualV2.pdf) gives you the pin numbers for the parallel port. It gives info on the motor connections, which you may want to cross reference with the info on the pac-sci website. They provide a generalised installation guide (http://www.pacsci.com/support/documents/stepper/powermaxinstallbulletin.pdf) which I think is suitable for all PowMaxII steppers, although you should confirm this yourself by having a look around their web site.

11-02-2003, 03:41 AM
How can i tell which pin in my motor is phase 1 out?

11-02-2003, 08:20 AM
Go to page 54 of this:


Phase 1 is pin 6.
Phase 2 is pin 1.
Phase 3 is pin 8.
Phase 4 is pin 3.
Tie pins 2 and 5 together, this is you're phase 1 and 2 power.
Tie pins 4 and 7 together, this is you're phase 3 and 4 power.

I don't have this board, I just read the manual and the Pacsci .pdf above and this is what it appears to be to me.


11-02-2003, 12:02 PM
Thanks alot man, you really helped.

11-02-2003, 09:44 PM
How can i find out the rated voltage on the motor?

11-02-2003, 10:15 PM
Usually written on the motor name plate. If the Amps and ohms are on there it's amps times ohms


11-03-2003, 05:01 PM
I only see the amps, there isn't any ohms listed on the label

11-03-2003, 07:32 PM
can you measure the ohms with a ohm meter? If so post it here and also the current.



11-03-2003, 09:10 PM
3.3A, 0.76ohm, = 2.5V when wired unipolar.


11-03-2003, 09:42 PM
Is there any way i can lower the AMPs on the motor, because my control card only support up to 3.0AMPs, and the motor is 3.3 AMPs. Also is there any power supply that you can recommend to me that is 2.5v?

Thanks guys for all your help

11-03-2003, 11:27 PM
go here to learn about steppers in general and how to use them with power supplies above the motor rated voltage. Pay attention to the unipolar tutorial.

With the right resistors you can run those motors at 3 amps and 24 volt powersupply.


11-09-2003, 03:53 AM
i am sitting here for more than 2 hours, but yet to finger out the right power resistor. Please help

11-09-2003, 01:42 PM
Just do a google search for stepcalc102 you'll find a program to calculate the resistors.
I was'nt able to attach it but you'll find it..........................Jim

11-10-2003, 08:50 AM
Originally posted by jimini
Just do a google search for stepcalc102 you'll find a program to calculate the resistors.
I was'nt able to attach it but you'll find it..........................Jim

Thanks for the info. I wasn't able to find the program, but i'll keep searching for it. If anyone find the program please post it here.

11-10-2003, 08:59 AM
A quick google for stepcalc102 found me this:
Hope it helps, I didn't test it though!

11-10-2003, 01:39 PM
I wrote steppercalc. It's also available on my website here:



11-10-2003, 08:38 PM
Hey guys thanks for the links. I'm trying to get everything right, so please stay with me. As I said above, I am trying to get 3.3amp motors to work with my 3amp controller.
On the motor calculator
1. On where the motor amp is I should put 3amp right? (Since I wanted 3amp)
2. I am trying to use computer power supply, so the voltage is 5v or 12v right?
3. Will the computer power work for 3 of my motor at 3amp/each?

11-10-2003, 11:12 PM
1) right
2) right, probably 12 volts
3) probably not. If your motors are 3 amps each times two windings that's 6 amps per motor. You will likely need 3 powersuplies, one for each motor. Make sure your controller can use seperate power supplies for each motor. Do NOT connect the powersupplies in parallel.

Does that controller use FET's or transistors for output?

If transistors, I get 2.87 ohms at 25.8 watts at 12 volt supply

If you use 3 ohms, 25 watts resistors your motors will draw 2.9 amps. I would shoot for that. Put the resistors on a LARGE finned heatsink with a fan.

For FET's use a 3.3 ohm, 25 watt resistor.


11-11-2003, 12:39 AM
2 resistors means one resistor for phase 1,2 and one for phase 3,4 right? Just did a search for some power resistors at Mouser.com. Is this the right resistor?resistor (http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=270792&e_categoryid=15&e_pcodeid=02817) by the way what is the 1% mean

I don't know what FET's are, but i'll just use resistors.


11-11-2003, 10:24 PM
If a diode is placed in series with each switched lead of the stepper, would it be appropriate to enter (in steppercalc) .6v less than the supply voltage, due to the voltage drop across the silicon junction?

TIP120's are darlingtons. What voltage drop can be expected across each transistor.....1.2v? Or is that already considered by steppercalc?

The reason I'm asking is, that the values listed in this discussion are almost exactly what I am planning to use. I have 3A, 3V, 1ohm, 191 oz-in. (Vexta PK268-03A) steppers. I have the steppers turning now using a 12v supply, a 2 ohm 25W resistor on each phase. Is this close? I'm using Kleinbauer's Piker.

The motor and 'sinked transistors get somewhat warm, but you don't want to touch the resistors! I've got the 'cement' resistors and I'm still trying to figure out the best way to mount them on a heat sink. I can line up 4 resistors over a Pentium4 heat sink/fan. Would RTV silicone conduct heat adequately, or is it an insulator?

11-11-2003, 11:29 PM
2 resistors means you are using 2 per motor. 1 resistor means you are tieing the center taps together on one resisitor.

1% means it is accurate to 1% of its rated resistance.

You controller will use transistors or FET's to switch the windings on and off. Transistors drop about 1 volt across them, fets do not, so the calc is a little different for each.

Steppercalc subtracts 1 volt from the ps voltage if you are using transistors, it ignores the voltage drop across a FET.


11-12-2003, 08:18 PM
The resistors mentioned look like wire wounds. Doesn't this increase the inductance, as it is in series with the motor winding, which defeats the object of running higher than rated voltage to improve the slew rate. The higher inductance brings the slew rate problem right back again.
I have not used power resistors, so don't know how much effect the increased inductance has.

If anyone has/ is using these. How do they perform against running with the motors at the rated voltage and no current limiting?

11-12-2003, 10:19 PM
The very small winding on the resistor causes a negligable amount of inductance.


11-16-2003, 01:08 PM

I decided to use one resistor. Here is the result for the calculation 1.43ohm, and 51.60watt. will 1.5ohm and 50watt power resistor work?