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This photo shows the Curtiss-Wright Embedded Controls M6000 (VR6211)-VXS I/O controller with dual XMC/PMC and Fibre Channel.
By John Keller
VMEbus Switched Serial (VXS) embedded computer technology continues to see niche applications for small, space-constrained military and aerospace electronics uses -- such as deployed image processing and unmanned aerial vehicles (UAVs), but is seeing its growth potential being eclipsed by its more capable cousin known as VPX.
Among the reasons for the market stability of VXS technology is its ability to form an applications bridge between venerable VME embedded computing technology and VPX. VXS offers faster, more capable computing than VME, yet enables designers to combine legacy VME and VXS single-board computers in the same chassis.
"There is a lot of VME 64 out there, and VXS offers an evolutionary upgrade, where VPX is more of a revolutionary upgrade," explains Tom Bohman, product for Curtiss-Wright Controls Embedded Computing in Leesburg, Va. Bohman is located at the Curtiss-Wright offices in Houston, formerly known as VMETRO.
"If you need a little more power than VME, and have relatively few high-speed links, then VXS offers an attractive alternative," Bohman says. "You have a band in the market there with a lot of familiarity with VME."
VXS, which refers to the ANSI/VITA 41 industry standard, combines parallel VMEbus with enhancements to support switched serial fabrics including PCI Express, RapidIO, StarFabric, and InfiniBand over a high speed P-zero connector.
VXS maintains backward compatibility with older technologies like VME with existing backplanes that do not have a conflicting P-zero scheme. Combining the VME2eSST parallel bus with switch fabric technologies for multi-point, high-speed data transfers creates choices for embedded computing designs of all types.
"You have folks that clearly have a lot of VME investment that are looking to use some sort of network fabric on the backplane; the sweet spot is Gigabit Ethernet, which is ubiquitous," says David Pepper, product manager for single-board computers at GE Fanuc Intelligent Platforms in Huntsville, Ala.
"People typically are trying to use a multitude of single-board computers for radar or image processing, and may have one or two switches and some ancillary boards in the other slots," Pepper says. "We have taken some of our VME single-board computers and put in the VXS P-zero connector. It's not hard for us to drop that in."
Primary applications of VXS include high-performance analog digitizers with field programmable gate array (FPGA) processing close to the digitizers. "We see applications at the low end, such as signals-intelligence listening systems, and those applications integrated in a small number of cards," explains Andrew Reddig, president and chief technology officer at TEK Microsystems Inc. in Chelmsford, Mass.
"VXS lets us use high-speed FPGA cards for processing, and then once the data is reduced to where it is manageable over a network, use Gigabit Ethernet for the last stage of computing among single-board computers," Reddig says.
Officials at TEK Micro see growth in the VXS market. Reddig says. One positive development is work on the Vita 41.8 standard, which will enable VXS to use 10-Gigabit Ethernet, he says.
Other VXS providers say VXS fill only a niche in high-speed embedded computing applications, as VPX grows in popularity. "I have a hard time envisioning a lot of growth in VXS," says GE Fanuc's Pepper. "It will be very nichey in applications in the control room, or in back-room processing that need the solid VME control plane with a scalable data plane."
Substantial amounts of VXS work have involved research and development laboratories that are not looking to deploy the technology," says Jim Tierney, vice president of government systems at backplane databus and chassis supplier Carlo Gavazzi in Brockton, Mass.
"We don't see much in VXS, and we don't see any follow-on deployment," Tierney says. "We thought it would be a good bridge product from VME before VPX really took off, but we are just not seeing it. We did not see the hybrid effect that we had expected to see."
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