PXI DMM, DAQ and Digitizer

[riie]

I'm a complete beginner to data acquisition to PXI data acquisition card and Digitizers/Oscilloscopes.

Forgive me if I asked anything dumb.

My purpose is to measure peak-to-peak voltage with a frequency less than 20khz.

Conversion must be done if DMM/DAQ is used as both of them give a RMS reading.

Digitizers such as PXI-5922 allows you to see the waveform in which Vpp can be measure but I believe the DMM PXI-4071 can also function as a digitizer?

So what are the differences between all three of them? Accuracy?

Thanks all!

[crossrulz]

That 5922 is definately going to give you the best accuracy.  But it is another card.  You can get a waveform out of the DMM and the DAQ as well.  If you already have the 5922, use it.  If not, I would try to get the DAQ to return a waveform.  With the waveform, you can process it however you want.

What DAQ are you using?  Or is it the DMM?

[riie]

The DAQ that I had is a PXI-6363.

I'm wondering should I use another module for the voltage measurement instead.
What are the differences between all the three and a Digitizer costs so more than a Dmm.

[crossrulz]

As I already said, configure your DAQ to acquire a waveform and read it in. 

Quickly looking at the specs, your accuracy would go in this order (best first) when digitizing a waveform: Digitizer, DAQ, DMM.  If you don't already have the digitizer, use the DAQ.  Save some money.