intermittent serial visa problem LV6.1

[McKenzie]

I have an application where serial communications using VISA work flawlessly most of the time. Very occasionaly, I see a strange (to me) VISA error during VISA reads. The error code is BFFF0030 (dec: -1073807312). This apparently translates to User Abort. But the user (me) is not aborting anything.

When I initialize the serial port I set the baud rate to 115200 baud, with no termination character. Other than that, I am using defaults. In the VI that does the read, I use property nodes to set the Serial End Mode for Reads and the Serial End Mode for Writes both to "None."

Setting the execution priority of the VI which does the reading to "Time Critical Priority (Highest)," greatly reduces the frequency of the problem.

I am
using a four-port serial card provided by the same vendor as the computer system. The driver for the serial card was also provided by the system vendor. I am using LabVIEW 6.1 on Windows 2000.

I was able to duplicate the problem on a totally different system by dragging a LabVIEW window around very rapidly with the mouse during the serial communications.

I would appreciate any suggestions or insights into this problem which anyone might have.

--McKenzie

[A.S.]

Hi McKenzie,
Based on your message and the test that replicates the problem, it is an issue with the memory. How much RAM do you have? Do you have a while loop in your VI? If so, you need to make sure that it has some sort of time delay in it, even if it is 1ms. I would recommend using the Wait Until Next ms Multiple VI with a 1ms time delay. This will prevent the VI from trying to use 100% of the processor.
The "user abort" means that the calling VI quit, not necessarily you. So I would check your VI for memory issues. You can check some memory usage in File>>VI Properties>>Memory Usage.

Hope this helps.

A.S.