Chapter 1 Overview of NI-VXI
© National Instruments Corporation
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NI-VXI User Manual
register. Devices that do not have bus master capability always transmit
such information via interrupts, whereas devices that do have bus
master capability can either use interrupts or send signals. Some
devices can receive only signals, some only interrupts, while some
others can receive both signals and interrupts.
The VXIbus specification defines Word Serial commands so that a
Commander can understand the capabilities of its Servants and
configure them to generate interrupts or signals in a particular way. For
example, a Commander can instruct its Servants to use a particular
interrupt line, to send signals rather than generate interrupts, or
configure the reporting of only certain status or error conditions.
Although the Word Serial Protocol is reserved for Commander/Servant
communications, you can establish peer-to-peer communication
between two VXI/VME devices through a specified shared-memory
protocol or simply by writing specific messages directly to the device’s
Signal register, in addition to the VXI/VME interrupt lines.
MXIbus Overview
The MXIbus is a high-performance communication link that
interconnects devices with a cabled communication link for very
high-speed communication between physically separate devices. The
emergence of the VXIbus inspired MXI. National Instruments, a
member of the VXIbus Consortium and the VITA organization,
recognized that VXI requires a new generation of connectivity for the
instrumentation systems. Additionally, National Instruments realized
that the same technology could be used also for the VMEbus, which is
the foundation technology under VXI. National Instruments developed
the MXIbus specification over a period of two years and announced it
in April 1989 as an open industry standard.
MXI-2 Overview
MXI-2 is the second generation of the National Instruments MXIbus
product line. The MXIbus is a general-purpose, 32-bit, multimaster
system bus on a cable. MXI-2 expands the number of signals on a
standard MXI cable by including VXI triggers, all VXI/VME
interrupts, CLK10, and all of the utility bus signals (SYSFAIL*,
SYSRESET*, and ACFAIL*).
