VXS Backplane: Part II

In a previous newsletter, I provided some details on the VITA 41 VXS specification. Since then, the specification has been revised. So, we will recap the basics of the specification and provide some details on the changes since the last newsletter.

VXS was created to provide a switch fabric path for system designers who want to keep VME compatibility. P0 in the VME slots is replaced with a high speed MultiGig RT2 7-row connector on the payload boards. The connector can easily handle 5 Gbps speeds, and will be used for the switch fabric traffic. J1 and J2 still use the160 pin DIN connectors, and the backplane accepts standard VME64x legacy boards. The hub (switch) slots use MultiGig RT2 connectors and a power connector. The backplane fabric topology can be single star, dual star, or mesh.

The major change to the specification since the previous newsletter on VXS is to the power connector. A bladed connector was originally written into the specification. It turned out the bladed connector mechanically interfered with conduction cooled boards. Military/COTS vendors requested a solution and a Positronic VP series connector was accepted by the task group. The VP series connector supports live insertion and extraction with 3 levels of sequential mating. Its compact size was designed for use with IEEE 1101.1, IEEE 1101.2 and PMC cards according to IEEE 1386.

A major change from the board perspective is to the J0 connector. The J0 connector had a similar problem as the power connector. It caused problems with conduction-cooled boards and interfered with PMC modules. The connector was modified to work with the two technologies. The backplane connector remained the same. (-more-)