Hello Mike!
NI-VISA cannot be the device driver for PCI-PCI bridges. There are a few reasons for this. First, the underlying driver for VISA's PCI resources, cannot be the driver for a PCI-PCI bridge. The reason is because PCI-PCI bridges are typically managed by the OS. To access the PCI-PCI bridge, you will have to develop a Windows driver.
We encountered this problem head-on a couple of years ago. Through lots of experimentation, we determined that different Windows variants handle bridges in very different ways. While we tried tried to follow all of the rules for writing a device driver on each Windows platform, some of them wouldn't give full access to PCI-PCI bridges (WinNT 4, for example). All this to say that this is a difficult problem,
and the PCI-PCI bridge configuration interface isn't ideal for implementing application-specific functionality.
Julianna Forrest
Applications Engineer
National Instruments
www.ni.com/ask