Synchronizing or something else?

[dion123]

Hello All!

i am new at labview and pxis so i dive straight in my problem. i have a digitizer NI-5122 connected to a signal gennerator, as well as an AWG NI-5421 connected to an oscilloscope. I want the 5122 sample the signal from the gennerator, process it with labview and visualize it in oscilloscope through 5421. I have used the examples that the pxis come with, but i have problems combining them. More precisely, my logic is gathering samples in an array, processing it and then AWG extracts the array to oscilloscope(but unfortunately i am doing it with no success). I use sequence structure so that one frame comes after the other.

So here my questions come: Do i need to synchronize the pxis? And if so, how can i initiate the AWG after the digitizer? Or if my perspective is wrong, can you give me any ideas to start with because i am really stuck at it..is there any sample code that i could study? thank you in advance and sorry for my english

Dionysia

[GovBob]

Dion,

 Your question is a bit confusing. The 5122 is a digitizer/Oscilloscope and though I don't have that particular model I'm guessing that you would use the NIScope driver for it. There should be no reason to use a external O-scope as long as you meet the input specifications of the 5122 with your signal generator.

hope this helps.

[micahmcc]

Hi Dionysia,

As GovBob said, you can use the NI-SCOPE driver to program with your PXI-5122 Digitizer. You will also use the NI-FGEN driver for your PXI-5421 AWG.

Here are some getting started resources for NI-FGEN and our Signal Generators and getting started resources for NI-SCOPE. Those two links will take you to some manuals that cover the basics of these two topics. These will be helpful for future reference.

That being said, let me make sure I am understanding your question correctly. You want to generate a signal with a benchtop signal generator, read that into LabVIEW with the NI-5122, then re-generate that signal with the NI-5421 to be read by a benchtop oscilloscope. Is there a particular reason you want to use this setup?

To answer your questions:

1) No, you do not need to synchronize your PXI modules for this application. I am assuming you are going to be writing the digitized samples to an array or a file, then using that file/array as the datapoints for the NI-5421. 

2) You can use LabVIEW dataflow (the error wire controls data flow) to initialize your digitizer then the AWG. 

If you have NI-FGEN and NI-SCOPE installed on your computer, you can access many examples through LabVIEW by going to "Help -> Find Examples", then browsing "Hardware Input & Output -> Modular Instruments". Within that folder are examples for NI-SCOPE and NI-FGEN. There is also ni.com/community.

I hope this answers some of your questions, let me know if you have any more!

Micah McClelland

National Instruments

Applications Engineer

[dion123]

Thank you very much both of you! I will follow your ideas. after searching, i also found this example that is close to what i want to do : http://zone.ni.com/devzone/cda/epd/p/id/2569#0requirements

I am sure that new questions will come up , so i might bother you again!

Dionysia

[dion123]

Hello again!

First of all, I hope you are fine.

i am working on the example of my previous post but we use in university lab pxis 5122 and 5421 instead of 5112 and 5411. As these two pxis function work in the same sample rate and there is no need for interpolation, i removed the interpolation vi. Unfortunately, the final regenerated signal isnt correct. i cant figure out what i am doing wrong. i am attaching my labview code so that you can give a look at it.

I dont want to be rude or take advantage of your help, but i am confused with this problem for quite a longtime. thank you in advance.

Respectfully,

Dionysia

[micahmcc]

Hello Dionysia,

Does that code work without modifying it? Can you explain exactly what is wrong with the final regenerated signal? What are you expecting to see (versus what you actually see)?

Also, those two cards were selected for another reason, do your cards have the same ability?

• Another feature of the NI 5411 and the NI 5112 is that they are synchronized so that the clocks are running in step by being phase locked looped (PLL) together.

I think more detail as to what you are changing and what the final results looks like might help us understand the issue better.

Thanks!