Stepper motor using analog signal

[Joe_Szalko]

Hi everyone,

I have a really simple problem that is giving me alot of trouble. I'm trying to run a stepper motor off the analog output of an NI USB-6211 DAQ device. I wrote a simple test code using the signal express VI and DAQ VI to control the motor. While the output graph displays the waveform that I need to control the stepper motor, the motor doesn't move. When I activate the program I can hear the motor buzzing, very faintly, which tells me that the program works and the motor is triggering properly but there isn't enough power to the motor to charge the coils. Since my motor needs +/- 3.2V to trigger (and the DAQ device supposedly outputs up to +/- 10V) I don't think that the voltage is the problem. The only thing I can think of is that the DAQ device doesn't actually output this voltage but I don't know anyway to check this.

If anyone has any ideas on how to solve my problem, it would be a great help.

I also uploaded my VI's for reference.

[Dennis_Knutson · Accepted solution]

Well, you check the voltage with a voltmeter.

Have you looked at the current requirements? You suspect that there is not enough power and power is equal to voltage times current. What does the 6211 spec say is the maximum output current?

[Joe_Szalko]

Well I feel foolish, I couldn't find the current requirement for my motor before because it isn't listed in its spec sheet but it has a power requirement and back calculating proves my hunch that I don't have enough power. Thanks for getting me to look at that again.

FYI USB-6211 has an output current of 2 mA per channel for a total of 4 mA across the entire device.