VXI & VXI-4

VXI – (VME eXtension for Instrumentation): The demand for a compact, both flexible and fast industry-standard instrument-on-a-card architecture has driven the development of the VXI standard. The modular form factor, high bandwidth, and commercial success of the VMEbus made it particularly attractive as an instrumentation platform. The tremendous popularity of GPIB also made it attractive as a model for device communication and instrument control protocols. The VXIbus specification combines VMEbus with GPIB features and covers packaging requirements, electromagnetic compatibility, power distribution, cooling and air flow for VXIbus chassis and plug-in modules.

The new VXI-4 standard adds VME64x and VXS technology to the VXI architecture by using VME64x style 5-row DIN connectors and adding 3.3V as supply voltage.VXI-4 mainframes and backplanes also implement LVDS lines LCLK100 and LSYNC100 as well as the LVDS Star Trigger from the VXI-4 standard. Optionally MultiGig RT 2 connector for switched fabrics can be added as P0 connectors.

VXI crates/mainframes and modules come in 2 form factors – C-size (6U x 340mm) or D-size (9U x 340mm). VXI uses the full 32-bit VME architecture but adds lines for instrumentation signals to the outer P2 connector rows (VME: user defined) and to the P3 connector of the D-size backplane.

Powered VXI mainframes for 19″ rack installation typically provide 13 slots. In order to be used for sensitive, analog test instrumentation VXI crate power supplies have lowest-noise requirements.