VME extension - VXI for instrumentation

What is VME?

The VME bus standards are governed by the VME Standards Organisation. The 32 bit VME bus offers a maximum bandwidth of up to 40 MB/s. The 64 bit version was developed in 1995 which increased the bandwidth to 80 MB/s.

What is VXI?

VXI is the VME extension for instrumentation.VXI was launched in 1988 and combines VME with the timing, triggering and synchronization features needed for instrumentation applications. VXI allows equipment from different vendors to work together in a common control and packaging environment.

VXI architecture:

The VXI bus architecture is an open standard platform for the automated test based upon VMEbus. It defines additional bus lines for timing and triggering as well as mechanical requirements and standard protocols for configuration, message-based communication, multi-chassis extension, and other features.


The basic building block of a VXI system is the mainframe or chassis. This contains up to 13 slots into which various modules (instruments) can be added. The mainframe also contains all the power supply requirements for the rack and the instruments it contains.

Instruments in the form of VXI Modules then fit the slots in the rack. It is, therefore, possible to configure a system to meet a particular requirement by selecting the required instruments.

Advantages of VXI:

  • Compact test solution due to the fact that all test instruments can be contained in a card inside a multi-welded frame.

  • VXI is an open standard and allows the use of instruments from a variety of manufacturers.

  • High speed operation resulting from the use of a single high speed rack and backplane.

  • The precise synchronization capability and synchronization as a result of possible high-speed communication between the instruments and the available activation facilities.

  • Ease of configuration resulting from the plug-and-play software.