NI-VISA 3.0 (coming out soon) will support USB, but only on Windows 98SE, ME, 2000, and XP.
We will have 2 levels of support. First, there is an instrument class specification (USBTMC) that was recently approved that defines a 488.2 class protocol. No instruments that support this protocol are yet available on the market, but I know they are in development, and NI-VISA 3.0 will support them.
NI-VISA will also support class-less devices that do not have other Windows drivers (only 1 kernel driver can "own" a given USB device). We have a wizard that will let you bind a given USB device to NI-VISA. Then you will be able to perform USB writes and reads and control port transfers. This will be similar to SOCKET communications, where you must be intimate
ly familiar with your device's protocol.
Dan Mondrik
Senior Software Engineer, NI-VISA
National Instruments