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, National Instruments announced Revision 1.0 of the PXI specification. In March 1998 the specification was endorsed by 15 companies, primarily system integrators. In June 1998, the PXI Systems Alliance (PXISA) was formed to discuss and promote the use of PXI as an open standard for data acquisition and instrumentation. Several instrumentation companies have joined the alliance and developed PXI products.
As of August 2000, the PXISA voted to accept ownership of the specification, and to adopt a new revision, Rev. 2.0. Further revisions to the specification are anticipated over the next few years as the PXI Systems Alliance addresses other inherent design issues.
Committees have now been established to deal with the issues of:
1. Heating and Cooling (VXI has a comprehensive standard, PXI merely states adequate cooling must be provided.)
2. IPMI and system management (software)
3. Configuration and control of PXI resources (software)
4. Creating a 6U standard (a move highly supported by Racal in order to create a more meaningful instrument platform)
VXI has the volume required to remain viable for years to come. As an evolving new technology, PXI is dependent on the Compact PCI volume to develop economies...