## VMEbus Card Form Factors

VME Board Sizes; Mechanical Dimension for VME cards

The graphic shows the four common board sizes used with VME.
However an adaptor card could always be used to re-format a 3U card into a 6U card.
A 3U to 6U adaptor card would accept the 3U card from one end but plug into both connectors of a 6U size board.
Of course the P2 connectors which make up the other half of a 6U interface would go unused.

Three basic VMEbus card [Dimensions] sizes are shown above, which include 9U, 6U, and 3U. Two 6U card sizes are depicted.
The VME64 spec added the P0 connector between P1 and P2 on the 6U size card (not shown).

IEEE 1101.1 Base Document for Mechanics ~ Defines 3U/6U/9U (high) x 100/160/220/280/340/400mm (Long) cards
IEEE 1101.10 Mechanics for VME Boards and Subracks
IEEE 1101.11 Mechanics for Rear Transition Modules [discussed below]

Three card heights are allowed with VME; 3U, 6U, or 9U; a single slot card is 6T wide. Length is either 160mm or 340mm (Norm)
Height is given in 'U' [1U = 43.60mm], Length is given in 'mm', Width is given in 'T' or HP [1HP = 5.08mm [HP: Horizontal Pitch];
Card sizes listed below are one slot or 6T wide
A size CCA dimensions = 3U x 160mm. A 3U Printed Wiring Board [PWB] is 100mm high.
B size CCA dimensions = 6U x 160mm. A 6U Printed Wiring Board [PWB] is 233mm high.
C size CCA dimensions = 6U x 340mm, ... {H x L x W {@ width=6T}
D size CCA dimensions = 9U x 340mm. A 9U Printed Wiring Board [PWB] is 360mm high.
A, B, C, and D are VXI terms. VME normally only references 3U or 6U [dimensions] by a length.

The board thickness for VME cards is 0.063 +/- 0.008 inchs [1.6mm +/- 0.2mm] Thicker or thinner CCAs may not fit in the card guides correctly.
How ever an 0.90 board may work if you mill down the top and bottom [2.5mm] of the card to 0.63 so it fits in the card guides.

A, B, C, and D are VXI terms. VME normally only references 3U or 6U by a length, but the 9U was added a few years ago.
The VMEbus PWB Dimensions [size] or form factor is also called the Euro-card form factor.

Back to the main VMEbus page for additional details including connector types, bus pin outs, and electronic equipment manufacturers and component manufacturers.
OEM VME Card Vendors, and products listing is found on the VME Board manufacturers page.

Note you could use an extender board so a C size card could be used in a D size slot [a slot adaptor].

Rear Transition Module: A board that plugs into the rear of a backplane and is used to transition the signal pins into another format.
A Rear Transition Module normally has the same height as the main boards plugged into the front of the backplane, but is not has deep as a normal card.
The transition card plugs into P1, P2 or P3 and outputs those signals over different style connectors, not the DIN type connectors used by the boards.
A transition card would be used as an interface between the DIN connectors on the backplane and D-type or circular connectors on the rear of the chassis.
The card could also be used to add buffering or some other function not found running directly off the backplane.

Break Out Board: A BOB card is similar to a rear transition module, but is much smaller.
A BOB card is normally just slightly taller than the P2 connector and used to Break-out or transition the DIN signals into another connector format.
The BOB-card would have a DIN connector on one side of the card and one or more other connectors on the rear of the card.

Abstract: Available VME board sizes. What are the VMEbus board formats. Show the different VME Card form factors
Compare the different VMEbus board dimensions. Comparison of VME card lengths and card heights. What is the depth of a VME board.

Modified 3/05/12