how to make AI acquire Waveform stop scanning...

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Hi... i'm using labview 7.1 and playing a DAQ hardware now...

i wish to know how to make the "AI Acquire Waveform" stop scanning data into waveform, i heard someone said that got a build in fuction to stop it... can anyone tell me is it true? If no, can let me know the method to stop it?

with regard
Jaxx

[dpacaba]

Hello Jaxx:

"AI Acquire Waveform.vi" will automatically stop depending on the "number of samples" you provided.

Probably that "someone" you said is mentioning about "AI Clear.vi". "AI Acquire Waveform.vi" has a built in "AI Clear.vi" inside it, so it means that it will stop on its own. 😉

I hope this helps. If you have any questions, please inform me.

[Otis]

If you have DAQ Hardware, LabVIEW 7.1, and are just starting to play with the DAQ software, then I would recommend that you try taking a look at some of the DAQmx routines instead of the Traditional DAQ routines. DAQmx tends to be simpler to understand and it is often easier to create applictions with it. That being said, some boards don't support DAQmx, yet, and in those cases you will have to revert to the Traditional DAQ calls.

Debonair is right about the number of scans though. The VI will keep running until it runs out of samples to take.

If you want to have a program that does continuous acquisition in Traditional DAQ and gives you the ability to stop it, try looking under Help >> Find Examples to get to the NI Example Finder. Then Browse to Hardware Input and Output >> Traditional DAQ >> Analog Measurements >> Cont Acq&Graph (buffered).vi That example should work for you and demonstrate how to create a VI that allows you to stop acquiring data whenever you want to.

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Hi Otis...
Hi Debonair...

Sorry about confusing you all... actually the "stop" i mean can say to "pause"... i wish the VI still running after press the pause button...
those signals still display on the waveform but only stop scanning(no move)... is it possible?

Another question here... from what Debonair said, AI Acquire Waveform will stop automatically depending of my "number of sample"... what is the result if i throw she in a while loop for running all the time? will it still continuous running? If not, have any solution about that?

[Otis]

If you want to pause your acquisition then the best thing to use would be Pause Triggering (DAQmx) or Scan Clock Gating (Traditional DAQ). You can find examples for either one in the NI Example Finder, search for 'pause' and go to the Cont Acq&Chart Samples-Int Clk-Pause Trigger.vi (DAQmx), or you can search for 'digital scan clock gating' in the search field for ni.com.

You may also want to look at this site for more information on triggering concepts: http://zone.ni.com/devzone%5Cconceptd.nsf/webmain/2A03115556FB233386256870005BB522

In your original comment you stated you simply want a pulse on one line to start, and then to pause the acquisition on the next, then repeat the operation. You may just need to use the Start and Stop Trigger examples reinitialize your task if this is the case where you are just looking at a pulse on one line. Pause triggering or Scan Clock Gating will relate more to you having a single line go high and staying high until you want to pause the acquisition.

Particularly if you are in the situation where you have pulses coming in on a single line I would recommend you look at the DAQmx examples rather than the Traditional DAQ examples. The architecture of the code is more efficient and will allow you to more quickly reinitialize the task.

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HI Otis...

thanks for your suggestion so much... i will try about what you had mention... if got any problem again i'll post message up here again, hope you can share your knowledge with me agian 🙂