Error -200279 of DAQmx

[Bill Choy]

Hi all,

Attached are two VIs for generate and measure signal with DAQmx. An error -200279 occurred when I measure harmonic distortion. There is no error if I turn it off. What's wrong of the program? I'm using LabVIEW7.1 and PXI-4461.

Bill

[Dr._Imad]

Please refer to the following discuusion thread for an explanantion of this error


http://digital.ni.com/public.nsf/3efedde4322fef19862567740067f3cc/7ad4854943bf344186256d6500807935?OpenDocument

You are probably generating huge amount of data at 200,000 sample per second, and the harmonic analyzer vi is creating delay (analysis wise) so your vi is not collecting data fast enough.

Refer to the examples that ships with labView on how to increase the buffeer size or increase the amount of scans to read (scan backlog). It will help

[Bill Choy]

Hi Dr.Imad,

I saw that the available samples per channel of DAQmx Read kept increasing when the program run. I set the input buffer to 1000000 but still no use because the used samples were accumulated. Any suggestions to solve this?

I didn't find any examples of using DAQmx buffer. Could you show me where to find? Thanks.

Bill

[alipio]

Hello Bill

I tested your test.vi using PCI-6025E on a Pentium 1.7Ghz and it runs fine.
A possible solution that I used when my PC was no so powerfull, was queues. The adquisition part fills a queue and, in a parallel process, the analisys part empties it and does its work. this and the use of different threads, can solve your problem.
Hope this helps.
Alipio

[Bill Choy]

Hi Alipio,

Did you use the multitone gen.vi to generate signal and turn on harmonic analysis in the test.vi?

I'm using PXI-8186 controller(2.2GHz with 512Mb ram) so that I don't think my system is a problem.

Any example for me to take a look of using queue in data acquisition? Thanks

Bill

[Dr._Imad]

I have attached a modified vi that will update the amount of scans to read in case of delay.
See the attached vi.

Also, it could that be plotting the data continuosly is creating more delay. You may want, if possible, to plot snapshots of it, it may help.

Hopr this helps.

[alipio]

Hi Bill.
I reproduced the problem in my PC. I think the problem was in your vi (some extrange incompatibility between HarmAnalyzer and Daqmx read). I erased the while loop and redid again and now It runs OK. Your PC can deal with theese vis in real time, as mine, using generator too.
See attached vi. I used LV7.0/nidaq7.2/PCI6052.
Hope it helps

Alipio