Hi rls,
You are correct. You will need to wait on the interrupt for each instrument. This may sound cumbersome, but with little effort, this can actually be fairly simple to program. I recommend you build an array out of the VISA sessions for each instrument. You could then pass this array into a for loop with auto-indexing enabled. Inside this for loop, you would place your VISA Enable Event and your VISA Wait on Event.
Regards,
David Shatila
Applications Engineer
National Instruments