Author: Christian Ganninger, Global Category Manager Systems EMEA
To satisfy the different requirements of systems in the market, CompactPCI has defined two board heights, 3 U and 6 U. In CompactPCI the electrical interface is accommodated in the 3 U space. The expansion to 6 U was defined in order to offer the user added value. This provides, for example, more than twice the amount of space on the board for the electronics. The front panels of the 6 U front boards and of the rear transition modules are also larger and thus allow a far larger number of front and rear I/O interfaces. Additionally, PICMG has defined additional buses in a number of sub-specifications in the 6 U space, for example PSB or H.110, which can be used in parallel to the CompactPCI bus.
CompactPCI Serial has adopted this CompactPCI concept and optimised it further. In CompactPCI Serial the electrical interface is again accommodated in the 3 U space. To improve signal integrity and reduce costs, the rear I/O signals are no longer passed through the backplane, but instead the front and rear transition boards are inserted directly into one another in the 6 U space. This also means that the user is not tied to a defined connector but can choose the one that best suits the application. Low-speed, high-speed and optical connectors are possible.
The user-specific signals can also be passed between the boards in the backplane. In this case the CompactPCI Serial connector is also used in the 6 U space. It is of course possible that future CompactPCI Serial sub-specifications will define standardised interfaces in this space.
To allow for the higher power demands of 6 U boards, additional power pins have been defined for 6 U backplanes; with these, 165 W capacity can be provided for each 6 U CompactPCI Serial slot. For telecommunications applications, an additional four 48 V pins are defined.