Generate DC voltage to control an electric motor

[igorgrz144]

Hello. I'd like some help to generate DC voltage to control an electric motor using a NI PXI-6221 M Series Multifunction DAQ and an SCB-68 Connector Block. I'm plugging one wire of the motor to "AO GND" and another to "AO 0". In LabVIEW 2017, using DAQ Assistant, I go to Generate Signals > Analog Output > Voltage > Channel ao0 > Generation Mode: Continuous Samples. Using Simulate Signal VI, I generate a DC Signal, offset 5 (let's say I want +5 V). Both are inside a while loop. That doesn't work. But when I plug one wire to "AO GND" and another to the constant "+5 V" pin of the connector block, it works. I think there's a problem with the generation of the signal in "AO 0". Could someone help me?

[santo_13 · Accepted solution]

Yes, it is because the output current of AO is limited (often under 10mA). You need a motor driver to handle the large currents required by the motor and you cannot control directly from just an AO (yes, it might seem possible but only in theory).

[igorgrz144]

It makes sense. Thank you for helping. You mean I need an amplifier to generate the current required, right? Should the PXI/PCI-73xx motion controllers do the job? It's a 12V brushed DC Motor.

[santo_13]

Motion controllers are the brains of the motion control system, they work with motor drivers to control motors.