I wrote a Labview app for a Keithley 34465A multimeter to be able to measure the current of a short biphasic current pulse. Initially I started with the NI drivers that are available, but they did not work. I could not even run the simple example VI to read a single measurement. The VI would time out on a read (error code -1073807339) after writing the SYST:ERR? command, and the next time I ran it, I would get error code -1073807360 on the Visa Open. After that, If I clicked on the VISA resource name control to refresh the device list it would just hang until I unplugged the 34465A from the USB. I also had to power cycle the 34465A or Windows would not recognize the device when I plugged it back in.
After working with the system half the day, and trying various commands using the NI-VISA Interactive Control application, I ended up abandoning the NI driver VIs (which were having issues with the same read after a SYS:ERR? write) and brute-forcing with the attached VI, which was working perfectly on Friday. I was able to repeatedly run the VI with no issues. My Errors array indicator would show +0, No Errors. I powered off all of the equipment for the weekend.
Come Monday, I powered everything up and tried to run the VI again. I'm back to the same issue I had on Friday where I get a timeout on the VISA Read after a Write of SYST:ERR?. Same situation, where I end up having to exit LabVIEW, shut off the 34465A, and start everything back up. I have no idea why this VI is failing, and why the same VI was working on Friday. Perhaps there was something I did in the interactive control app that fixed some problem?
FYI, I'm running LV17 with NI-VISA 19.2 running under Windows 7 Pro.