National Instruments VXI-USB - Manual (Page 10)

Chapter 1 Introduction
VXI-USB User Manual 1-2 ni.com
VXI-USB Interface Kit Overview
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.
Note 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.
Note 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.
VXI 3.0 Specification Support
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.
Hardware Description
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.
Note 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.