CompactPCI form factor
28
Model 6276 User Guide
3 • System architecture
panel interconnections. An illustration of the front-entry board and rear-panel I/O board interface with the
backplane/midplane is shown in
figure 10
.
Figure 10. Front/rear boards and backplane interface
Rear-panel I/O boards are either 3U or 6U in width and are typically 80mm in depth. Other depths are
allowed depending on the application requirements. The 2U chassis provides an 80mm transition module sec-
tion. This section provides four 6U x 80mm slots for cPCI transition modules.
All front-entry board features (handles, keying, alignment pin, EMC, etc.) are also utilized on the rear-entry
boards. The rear-panel I/O transition boards are “in-line” with the front-entry boards. This means that the
front panels of rear-panel I/O transition boards are reversed (mirrored) from the front boards. The top handles
are on the bottom and vice versa. The slot keying holes and hole labels in both the card guides and front panels
are upside down compared to the front boards and card guides.
The same connector pin labeling sequence is used on the rear I/O transition boards as on the front boards,
with the position numbers going from bottom to top. This is a mirror image of the front board’s layout orien-
tation. Using the same 1-for-1 pin mapping sequence eliminates confusion and I/O signal pin mapping prob-
lems. For example, pin A3 is the same on the front boards, on the rear I/O transition board, and on the
backplane.