Instrument Control (GPIB, Serial, VISA, IVI)
VISA usb interrupt freeze
I'm having a hard time finding the source of an error in one of my programs in the lab.
I have a set of drivers (written myself) for controlling what is essentially a HID over USB. It's actually a measurement instrument, not an actual HID but it identifies itself as HID.
I am reading the Interrupt data intermittantly since the actual changes in data occur only once per second or so, and it interspersed with status information after sending commands to the device. I am thus forcing the device to work in a request-response mode instead of typical HID behaviour (which in my eyes doesn't fit too well to the device anyway).
I see problems after 15-min to 4 hours where the LV program completely blocks up. I can't end the program at all, only a trip to task manager will do the job. The rest of my system is nice and stable, I can continue working after the freeze with any other program or OS function.
I have a sneaking suspicion that it's my interrupt code which is somehow getting "lost". I used to have an event structure in parallel to my device control loop but I got rid of this for testing, and the problem still occurs. I thought it was maybe a deadlock with the UI or something.
Can someone tell me if the following code should produce problems like this? I have multiple devices connected at once, that might be an important thing to mention (with the code shown being called one after another, not simultaneously).
I'm using LV 2009 (not SP1) with VISA 4.5.1 on WinXP 32-bit.
Regards
Shane.
