A Little Bit About PXI and VXI

Two other hardware platforms you should be familiar with are PXI and VXI.

PXI, an acronym for compactPCI eXtensions for Instrumentation, defines a modular hardware platform based on the Intel x86 processor (PC architecture) and the CompactPCI bus (a version of the PCI bus). A typical configuration involves a PXI chassis (such as the one shown in Figure 2.9), which holds its own PC computer (called a controller) running Microsoft Windows and slots for all types of measurement modules: analog input, imaging, motion control, sound, relays, GPIB and VXI interfaces, and more. The compact, ruggedized, and expandable system make it an attractive platform for many applications. Figure 2.10 shows a PXI system in a real-world application. In addition to a standard PXI configuration running Microsoft Windows on the controller, you can use the real-time version of LabVIEW (LabVIEW RT) on the controller for a more robust system, or even run Linux (support for NI hardware on Linux is steadily improving).

Figure 2.9. PXI chassis with controller and various IO cards installed

Figure 2.10. PXI system

VXI, an acronym for VME eXtensions for Instrumentation, is another instrumentation standard for instrument-on-a-card systems. First introduced in 1987 and based on the VMEbus (IEEE 1014) standard, the VXIbus is a higher-end and usually more costly system than PXI. VXI consists of a mainframe chassis with slots holding modular instruments on plug-in boards. A variety of instrument and mainframe sizes is available from numerous vendors, and you can also use VME modules in VXI systems. VXI has a wide array of uses in traditional test and measurement and ATE (automated test equipment) applications. VXI is also popular in data acquisition and analysis for research and industrial control applications that require high number of channels (hundreds or thousands).

VXIplug&play is a name used in conjunction with VXI products that have additional standardized features beyond the scope of the baseline specifications. VXIplug&play-compatible instruments include standardized software, which provides soft front panels, instrument drivers, and installation routines to take full advantage of instrument capabilities and make your programming task as easy as possible. LabVIEW software for VXI is fully compatible with VXIplug&play specifications.