VITA 41 vs. VITA 46 – A Closer Look

Although V41 (VXS) is quickly gaining more and more popularity, some in the industry have been waiting to see what happens with V46 (VPX). This is probably more out of confusion than anything else, and the VME community has not provided a clear enough message.

First, V46 is not a progression from V41, it is a different path for different needs. The two specifications might not compete often, and in some cases hybrids will be a good fit. At times, V41 will fit a niche better and other times V46 will fit another niche better. V46 is offered in both 3U and 6U providing high-performance in a small space. V41 offers backwards compatibility and the improved performance of switched fabrics.

V41 takes a standard VME64x slot and swaps out the 2mm HM connector in P0 for a high-speed MultiGig connector. A switch slot is added (or two in a Dual Star configuration), for high-speed connectivity and backwards compatible VME performance. V46 has all Mesh segments with the MultiGig connector filling the slots and replacing the DIN P1 and P2 connectors and the 2mm HM connector in P0. Therefore, it is not fully backwards compatible and the VMEbus is optional. However in hybrids, you can have a V46 backplane with standard VME64x slots next to the Mesh segment. In fact, has developed a concept VITA 46 backplane in this configuration. The 12-slot backplane has the VMEbus signals across P2 of the legacy cards continuing across the MultiGig mesh connectors. The upper section of the MultiGig connectors is reserved for high-speed I/O.

Now to confuse you again…the backplanes of both specifications can be made in very similar configurations. For example, with a hybrid V41, you can have a Single Star or Dual Star segment on a VXS backplane next to a Mesh segment or have a Mesh segment next to legacy VME64x slots, just like the concept backplanes Elma Bustronic did for V46! Of course, custom cards would need to be developed in this case. But, most V46 applications will be customized and many V41 as well. How about I/O pins? You can have more I/O pins on a backplane/cards with a Mesh segment with either architecture. Conduction cooling can also be implemented on both. So, you can see, the architectures can be implemented in very similar ways and to a degree complement each other.

Justin Moll
Dir of Marketing
Elma Bustronic
Jmoll@bustronic.com

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