XI vs PXI Automatic Testing Architectures
VXI has emerged as a powerful open architecture for automatic test systems in its short thirteen-year history. An evolving new standard for data acquisition and test called PXI has more recently gained a lot of attention. PXI marketers have been promoting PXI as a low cost replacement for VXI. This report examines the key differences between the two architectures and concludes that:
· VXI and PXI address two different market segments and will co-exist for many years to come
· Major ATE systems are currently best implemented using VXI
· VXI provides field proven reliability and minimal risk to major ATE customers
· High resolution, low speed data acquisition systems are best implemented using PXI
· Small, bench top or light weight portable test systems are suited to either architecture; customers should consider future ability to upgrade with existing module technology
VXI was designed in 1987 as an open architecture by a consortium of five major instrument manufacturers: HP, Tektronix, Racal, Wavetek and Colorado Data Systems. The USAF was instrumental in kicking off this effort.
VXI is based on the VMEbus, with extensions to facilitate high performance multi-vendor automatic test systems. VXI has more than a ten-year track record as a leading architecture for military and commercial automatic test systems.
PXI was designed in 1997 by National Instruments as an architecture for data acquisition instrumentation. PXI stands for Pci eXtensions for Instrumentation. National based PXI on the Compact PCI standard, adding features to address the unique needs of the acquisition and test markets.
In August 1997, Natio...
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...tectures are complementary, and each is suited to a different range of applications. VXI is generally more robust and suited to high performance functional test systems. PXI is generally suited to small systems requiring lower measurement accuracy and high data transfer rates such as data acquisition systems. Neither VXI nor PXI implementations are inherently less expensive. Costs are more closely correlated to the particular functionality required. Moving forward, these two architectures will co-exist, each exploiting their unique market segments.
Test system engineers must take into consideration all of the above issues before selecting between a XI, PXI or rack-n-stack platform. Each has their merits depending upon the complexity, density, signal speed, project life, upgrade plans, software, robustness, field support and availability that the project requires.