Why DAQmx read error 200714 when saving file?

[preschooler]

In the particular vi I am creating, I have 3 analog input channels come in and are graphed.  If I choose to save the information to a file, a dialog comes up and I can choose what to save it as.  If I take too long to save the file (aka about 8-10 sec if the sample read rate is 500/sec) then I get this error after the file has been saved :

   Error -200714 occurred at DAQmx Read (Analog 1D DBL NChan 1Samp).vi
   Possible reason(s):
   Acquisition has stopped because the driver could not transfer the data from the device to the computer memory fast enough. This was  caused by computer system limitations.
   Reduce your sample clock rate, the number of channels in the task, or the number of programs your computer is executing concurrently.

Why does the DAQmx read vi have this problem after the vi has been idle for about 10 sec while I choose where to save the file?  How can I fix this error?

[Andrew McL · Accepted solution]

Hi preschooler,

I think your error could be caused by the read buffer overflowing. my suggestions to you would be to do either of the four following ideas:

1. Stop the acquisition before you write the file. This should mean that the DAQmx Read function will no longer be reading and hence shouldn't generate the error.

2. If you want to carry on reading the data but also write data as well, I think you would be better suited to use the TDMS vis. TDMS allows the user to stream data to a filewhilst reading.

3. Setup the save file dialog before you begin the acquisition. Get the user to enter all the file data before you start acquiring.

4. Change the read buffer to unlimited so that you have sufficient time to navigate the save window.

If you send in your VI I can advise further,

Let me know how you get on,

[preschooler]

Thank you for your response.  That gives me some more options for some other vi's in the future.

As for this problem, I actually fixed it by freeing up the task before the file write and starting up the task again after the file write.  I was able to do this because I don't need it to acquire data during the writing process, just before it.  I haven't had any more errors since I did this.  It also doesn't take any noticible extra time.

Thanks again