Creating a task with NI9472 and counter from cDAQ9178 for PWM

[Freel]

Hello,

For a project I need to create a DAQmx task for PWM in my project library.

I have the NI 9472 Digital Out module with no counters, and a NI compactDAQ 9178 with 4 counters.

How can I configure the task so that I can use the counter from the cDAQ to output PWM from the digital out module?

Thank you and as always, kudos will be given! 

[Aaron_W.]

Giant,

I'm guessing you are programming this in LabVIEW? Either way, you really shouldn't have much trouble with this, the example I point out are in LabVIEW. You will natively be able to access the 9178 counters from your 9472 module. I simulated something similar to what you have:

From there, you just need to specify the Counter and Output Terminal in your program. There is an example in LabVIEW 2012 in the Example Finder called "Counter - Continuous Output" that I am using.

This will allow you to route your signal to the line you want. Now as for changing the duty cycle of the PWM, NI has a good white paper on the topic.

Pulse Width Modulation (PWM) Using NI-DAQmx and LabVIEW

http://www.ni.com/white-paper/2991/en/

Hope this helps.

[Freel]

Aaron_W thank you for your awesome reply!

[Xavrocg]

Hello,

I work with the NI 9472 Digital Out module with 4 counters assembled in a NI compactDAQ 9178.

I see in the default allocation of the module that:

- CTR 0 OUT is working on PFI3

- CTR 1 OUT is working on PFI7

- CTR 2 OUT is working on PFI1

- CTR 3 OUT is working on PFI5

Is it possible to modify this allocation with the following settings:

- CTR 0 OUT to work on PFI0

- CTR 1 OUT to work on PFI1

- CTR 2 OUT to work on PFI2

- CTR 3 OUT to work on PFI3 ?

If yes, what tool do I have to use to perform this operation?

Regards,

Xavier

[Freel]

Hello Xavier,

I don't think that the cDAQ is flexible enough to allow you to choose to which output a counter is connected to. I'm not 100% sure how this work, but the backplane of the cDAQ would need an expensive switching matrix to allow this. 

[mferguss]

Hi Xavrocg,

As previously mentioned it is possible based on the device to route to different locations on the device. Some if not all of this routing is possible. I have attached a couple of articles outlining the method you can do this:

Internally Routing Counter Signals:

http://digital.ni.com/public.nsf/allkb/8A85E97855EDADC98625730C00065F58

How Can I Know What internal routes are available on my device:

http://digital.ni.com/public.nsf/websearch/E539D226A643C1CE8625715E007C23C8

Kind Regards,

Matt Fergusson

[Freel]

Iqnore my previous answer, I was obviously wrong. Sorry about that.