How can I deal with error 200621 and 200279?

[zhenyiy]

Hi, I am new to Labview. I was asked to use Labview to do some basic frequency-domain analysis for my homework. The hardware I use is myDAQ student instrumentation device. Basically, I am asked to transfer audio signal from MP3 to Labview by using the audio in jack on myDAQ, and transfer the editted signal to a speaker by using the audio out jack. Also, I was asked to have a toggle to let users alter from music to white noise. 

Here's the problem. If I do not switch between white noise and music, it works well. But as long as I click the toggle, either error 200621 or error 200279 will appear. And I referred to the help file (http://digital.ni.com/public.nsf/allkb/AB7D4CA85967804586257380006F0E62), but I still have no idea how to solve the problem. Could anybody give me a detailed instruction, thanks.

vi file mentioned above is attached 

[zhenyiy]

Nobody wants to give me a hand?

[RavensFan]

Be patient!

You asked a question rather early in the morning for most of the people who frequent the forums.

Your errors are due to buffer overflows and underflows.  Your DAQ assistants are doing an analog input and an analog output of rather large datasets at a high bandwidth.  Plus you have some data filtering and processing going on in between.

You posted a link to an NI KB article, however that link seems to be broken.  It comes up "HTTP Web Server: Lotus Notes Exception - Entry not found in index".

I think you should try to avoid using the DAQ assistant and break it down to the basic DAQmx functions.

But more than that.  I think you should put your data acquistion into a separate loop from the analog output.  Pass the data by way of a queue.  This should make the both parts more tolerant of each other of any small or minor delays.

[aeastet]

I think I would use an event structure to start and stop the DAQ. When the switch is switched to DAQ then you start the digital stuff. When the user switches back then you stop and end the digital stuff. This way you do not have it running all of the time. It would also give you cleaner transitions between simulated and real data.

[zhenyiy]

Ravens Fan, thanks for your reply. I am a novice, and I do not know how to use basic DAQmx functions. Can you talk about it in more details? For example, what basic DAQmx functions do I need to include into the sequence? Also, what do you mean by "Pass the data by way of a queue"? Thanks

[RavensFan]

Take a look at:

Getting Started with NI-DAQmx: Getting Started with NI-DAQmx Programming in LabVIEW

Learn 10 Functions in NI-DAQmx and Handle 80 Percent of Your Data Acquisition Applications

You can also find a lot of DAQmx examples with Find Examples under the Help menu.

Also, if you right click on a DAQ assistant and choose Open Front Panel, it turns it into a subVI where you can look under the hood and see how the DAQ assistant is doing its job with the basic DAQmx functions.

For queues, look for examples for that as well.  And also look for the design templates under File / New... for Producer/Consumer architecture.  Also do more searching on the forums for questions and answers about queues and producer/consumer.