Error message

[smercurio_fc]

I think the confusion may stem from the fact that they're using the "LabVIEW <-> GPIB" example, which doesn't use VISA - it uses the straight GPIB functions.

[Alias007]

Yes, you are right. VISA and GPIB confusion.

When I use the VISA read and write function its working fine.

But in HFS9003 VI (from NI) it uses GPIB function to read and write  that's were the error happens.

[smercurio_fc]

You have to modify your address string as Dennis noted if using the GPIB functions and you are using a board with an id of 1 (or anything that's not 0). The Help file for the GPIB functions says:

When there are multiple GPIB Controllers that LabVIEW can use, a prefix to address string in the form ID:address (or ID: if no address is necessary) determines the Controller that a specific function uses. If a Controller ID is not present, the functions assume Controller (or bus) 0.