PCI E Xtensions For Instrumentation - Overview

Overview

PXI is designed for measurement and automation applications that require high-performance and a rugged industrial form-factor. With PXI, one can select the modules from a number of vendors and integrate them into a single PXI system, over 1150 module types available in 2006. A typical 3U PXI module measures approximately 100 x 160 mm (4x6") in size, and a typical 8-slot PXI chassis is 4U high and half rack width, full width chassis contain up to 18 PXI slots.

PXI uses PCI-based technology and an industry standard governed by the PXI Systems Alliance (PXISA) to ensure standards compliance and system interoperability. There are PXI modules available for almost every conceivable test, measurement, and automation application, from the ubiquitous switching modules and DMMs, to high-performance microwave vector signal generation and analysis. There are also companies specializing in writing software for PXI modules, as well as companies providing PXI hardware-software integration services.

PXI is based on CompactPCI, and it offers all of the benefits of the PCI architecture including performance, industry adoption, COTS technology. PXI adds a rugged CompactPCI mechanical form-factor, an industry consortium that defines hardware, electrical, software, power and cooling requirements, leaving nothing to chance. Then PXI adds integrated timing and synchronization that is used to route synchronization clocks, and triggers internally. PXI is a future-proof technology, and is designed to be simply and quickly reprogrammed as test, measurement, and automation requirements change.

Most PXI instrument modules are register-based products, which use software drivers hosted on a PC to configure them as useful instruments, taking advantage of the increasing power of PCs to improve hardware access and simplify embedded software in the modules. The open architecture allows hardware to be reconfigured to provide new facilities and features that are difficult to emulate in comparable bench instruments. PXI system data bandwidth performance easily exceeds the performance of the older VXI test standard. There is debate within the technical community as to whether newer standards such as LXI will surpass PXI in both performance and overall cost of ownership.

PXI modules providing the instrument functions are plugged into a PXI chassis which may include its own controller running an industry standard operating system such as Windows XP, Windows 2000, or Linux (which is not yet PXI System Alliance approved), or a PCI-to-PXI bridge that provides a high-speed link to a desktop PC controller. Likewise, multiple PXI racks can be linked together with PCI bridge cards, to build very large systems such as multiple source microwave signal generator test stands for complex ATE applications.

CompactPCI and PXI products are interchangeable, i.e. they can be used in either CompactPCI or PXI chassis, but installation in the alternate chassis type may eliminate certain clocking and triggering features. So for example you could mount a CompactPCI Network interface controller in a PXI rack to provide additional network interface functions to a test stand. Conversely, a PXI module installed in a CompactPCI chassis would not utilize the additional clocking and triggering features of the PXI module.