Hi everyone,
I am having some problems adding communicating via GPIB with three instruments at the same time. The three instruments are an Oxford superconducting magnet power supply, an SRS lock-in amplifier, and an HP 34401A multimeter (used to read the voltage output of an analog lock-in). The problem is my code runs for a minute or two, and then the Agilent evidently gets bogged down before timing out and spitting out an error on the front panel (error -410 "query interrupted"). I'm running this on a pretty old system (Win 2K, Labview 6.1, Visa 2.6.0) which doesn't help with the speed issue.
I have been running my code for a couple years now without any major problems (occasionally the DMM will give an error if I abort the program at the wrong point) - all the problems I have had have been fixed by shutting down all the electronics and computer and restarting everything. The problem is now when I try to add the SRS lock-in to the code. I can run the code witht just the SRS lock-in and magnet supply, and I can run the code with as many as three DMM's being read over the GPIB with the magnet supply. The problem only happens when I have the SRS lock-in and the DMM being read at the same time. My suspicion (based on the error message) is that one of the instruments is leaving some data on the communication bus somewhere, and it is overloading the DMM, though I have unfortunately not yet found what exactly is causing the overload. Does anyone have any guesses of what to try? The help documentation in Labview is unfortunately even older than the VI I'm using (some of the inputs in the "Initialize instrument" VI are different from what is shown in the help menu). Does anyone know if it is easy/safe to communicate more directly with the DMM than using the VI's included in Labview? I ask because the SRS lock-in, for instance, is really easy to read - you just write one VISA command and the lock-in returns whatever the front-panel of the instrument is reading. You can of course create more complicated codes to read or set other instrument parameters, but all I need to do is read a simple DC voltage -10 to 10V with the DMM, so anything I can do to make the communication faster/simpler would be good since right now my data resolution is pretty limited due to the lag in all the communication steps. Also, does anyone know if there is anywhere online I can access newer help files on the Agilent/HP sub-VI's since the help files on my computer are inconsistent with the VI's? Thanks!
