Using LabVIEW 5, I am trying to communicate with multiple HP34401As at the same time as an HP8719ET, with two independent VIs. I can communicate with any of the instruments individually and can communicate with them in series. I need to communicate in parallel, and every I attempt I make is thwarted by errors which seem to occur randomnly, within an hour of starting the VI that does the comms. If I use the one GPIB board I routinely get Error -1073807300. However I have no "Open Sessions"; my programs always "Close Session". (I notice that in LabVIEW 6, a boolean can be wired to the "Open VISA" function allowing duplicate sessions, but not in LV5). When I try two GPIB boards in the computer and only communicate with the HP8719 on
one and the HP34401As on the other, I randomly but routinely get Error -1073807339 from either or both instruments. I have tried using the "Wait" functions to prevent timeout conflicts but nothing seems to make any difference. In LV5 the "Open VISA" function has a timeout control but I don't know what I could wire to it. Can anyone help - this is very frustrating!