pwm digital output

[sunny dee]

Hi, I have a PCI-6221 M series card and I am trying to control 4 heaters with it. I want to create 4 seperate PWM signals on 4 of the digital output lines. The PWM frequency will be the same for all 4 heaters, however the duty cycle will change.

Any ideas on how to do this, or if you could point me in the direction of an example it would be greatly appreciated! All of the examples that I have looked at use the counter output, but since I have only 2 of these it will not work.

Thanks!

Sunny

[Justin_M]

Hi Sunny,

What is the frequency of these PWM signals you need to output?  Since you are controlling heaters, I'm guessing you'll be working with lower frequencies, in which case a software timed application could work for you.  I suggest taking a look at some of the digital generation examples in the NI example finder (if you're using LabVIEW).  Just open LabVIEW and go to Help >> Find Examples...  Then under the Browse tab, go to Hardware Input and Output >> DAQmx >> Digital Output.

If you are using a programming language other than LabVIEW, the best place to look is either in the examples shipped with the DAQmx driver (by default at C:\Program Files\National Instruments\NI-DAQ\Examples) or in the online Example Code Library.

Thanks,

Justin M.

National Instruments