I think what you are saying is that you cannot connect a string control or constant to a VISA VI. In LabVIEW 6i that is correct. To get around this you must use either a local reference or a sub-VI to essentially cast the string to a VISA refnum. This has been fixed in LabVIEW 6.1. With this latest version of LabVIEW, you can now directly connect a string constant to a VISA VI.
In either case (LabVIEW 6i or 6.1) MAX is not required. Just drop a VISA refnum I/O control on either your LabVIEW front panel or diagram.
You may need to right-click on the VISA control and select the appropriate class for the VI that you are trying to connect to. For most operations, the Instr class is sufficient.
Dan Mondrik
Senior Software Engineer, NI-VISA
Nati
onal Instruments