How can I use LabView to switch a motor on/ off?

[Kyle W]

Hi I was wondering how can I use LabView to turn a motor on / off and thus control the speed? It's a basic ac motor that is to be used to constantly turn a spindle.

Thanks,
Kyle

[Kyle W]

Sorry motor is DC.

Regards,
Kyle

[Jochen]

If you only need a very rough control of the speed you could use the counter of any multifunction DAQ board like the NI PCI-6220 to output a user definable PWM signal. Depending on the duty cycle of this signal the motor will move faster or slower.

If you need a more sophisticated type of control I would recommend using an appropriate drive and a motion control board like the PCI-7342 that runs a PID algorithm onboard.

Please provide more detailed information if you need a more detailed answer.

Best regards,

Jochen Klier
National Instruments Germany

[labview1958]

I am also interested in controlling a DC motor speed. Can you sent me a labview program controlling the speed of a DC motor with PWM. Also where do I connect the DC motor's, positive and negative terminals. Which PINS of the NI DAQ 6025E card? I am sorry if this messages repeats. There is some virus doing the REPEATS.

[Jochen]

The best way to output a PWM signal with your board is to use a counter output. For the pinout please refer to your user manual. Please note that using a DAQ board under Windows can only be used for very rough control tasks. For the case you need to implement a real closed-loop control algorithm this setup won't result in a stable system. There are two options:

1. Run the application in a LabVIEW Real-Time environment.
2. A much easier and in many cases much cheaper solution is the use of a dedicated motion controller (see above).

Best regards,

Jochen

[labview1958]

Can the COUNTER output go to 15 volts. Is it enough to drive a power drill? Or should the output from the COUNTER be used to CONTROL another circuit to drive a power drill? If so HOW?

[Jochen]

For this type of information PLEASE refer to your manual. The counter output is just a TTL output (+5 V). You can't draw power from the counter output. You need to connect it to an external amplifier.

Regards,

Jochen

[Brian_Beal]

You are going to want to buy a DC motor drive. They are rather inexpensive, and most will take a 0-10 VDC signal to control speed. This way, the 6025E handles all control and signal levels, while the motor drive handles the power to the motor.

[Jochen]

But again if you decide to go this way then a dedicated motion controller like the PCI-7342 will make your job so much easier and above all the solution will be reliable.
As I can't tell from the postings of this thread which level of control is needed here I won't dig futher into this issue for now.

Jochen

[labview1958]

I cannot afford to buy a PCI-7342 card. However I have already built two circuits based on an article on the net. I have attached the file in the PDF format. A friend has made a labview program in labview 6.0 based on the article. I have not yet connected the circuits to the 6025E card. I do not know which PIN to connect. Also I am concerned it might damage the card. Another friend says I only need ONE circuit as the DAQ card can give a PWM output of 10V controlled by inbuilt VI.

Sometimes the message will REPEAT twice or thrice. I apologize for the inconvenience.