The VI you attached doesn't seem right. You only have one Initialize function, and you are not wiring the correct string into it. It looks like you're trying to wire "GPIB::13 19", which is not valid.
You need to have two different sets of Instrument Driver VIs. Duplicate the three icons you have. Into one Initialize function, wire "GPIB0::19::INSTR". Into the other Initialize function, wire "GPIB0::13::INSTR". Brian
