Serial Communications - Frequent use crashes LabVIEW

[Ian Renton]

I have created a VI that sets up, reads from (twice), then closes a serial port, and provides an output based on what it recieves.

On its own, there is never a problem. However, when it is integrated as a Sub-VI in a larger system, and called frequently (around 100 times a second), LabVIEW crashes ("LabView.exe has performed an illegal operation and will be terminated..."). The execution time of the Sub-VI is around 3ms, so 100 per second should be easily possible.

Can anyone help here? Am I simply reading the serial port too quickly or too often for LabVIEW (or for Windows) to cope?

I'm currently running LabVIEW 6.1 but I do have the chance to upgrade to 7.0, would the upgrade help with this problem?

[Ray K]

It sounds like your subvi is in a loop and is opening and closing the port repeatly. VISA Open should only be called once at the beginning of the program and VISA close should be called once at the end.