National Instruments VXI-USB User Manual

The interface kit described in this manual links a USB-equipped computer 
directly to the VXIbus using USB 2.0. The VXI-USB kit uses this 
high-speed (480 Mbps) serial bus to link your computer running Windows 
to a VXI chassis.

You can use the VXI-USB kit with USB 1.0, but performance will be significantly 

slower than with USB 2.0 for many types of operations.

You can connect multiple USB devices to the host. However, increasing the number 

of USB devices in a system can lower the VXI-USB performance.

The VXI-USB kit includes the NI-VXI/NI-VISA software for Windows, 
a C-size VXI-USB module, and a USB cable. A USB-equipped computer 
connected to a VXI-USB interface can function as a VXI Commander and 
Resource Manager. With the VXI-USB interface kit, your computer 
performs as if it is plugged directly into the VXI backplane as an embedded 
CPU module. The VXI-USB transparently translates between USB and 
VXI protocols.

The VXI-USB has been designed for VXIbus Specification 3.0, and also is 
compatible with VXIbus Specification 2.0. The VXI-USB supports new 
VXIbus 3.0 features such as 2eVME transfers (with a theoretical 
bandwidth up to 160 Mbytes/s), A64 memory space allocation, and a 
Resource Manager that supports A64 allocation. NI-VXI includes an 
NI-VISA driver for the VXI-USB that has additional functionality for using 
these VXIbus 3.0 features. If you have a VXI device that supports these 
features, consult the VXI-USB release notes for information about how to 
access them from NI-VISA.

The VXI-USB module is a VXIbus Slot 0-capable device, so it can reside 
in slot 0 of any C-size or D-size chassis.

D-size VXI mainframes have connections for a P3 connector. The VXI-USB, 

however, does not have this connector and cannot provide the necessary control for VXI 
devices that need P3 support.