Author: Manfred Schmitz, Technical Director of MEN Mikro Elektronik
The original CompactPCI® architecture is based on a parallel bus which connects the system slot to the peripheral slots. PICMG 2.16 – a CompactPCI® extension – introduced Ethernet on the backplane as another transmission medium beside the parallel PCI bus. CompactPCI® Express turns away completely from the parallel PCI bus and is based exclusively on PCI Express as a fast serial point-to-point connection.
Another way of merging the different architectures is PICMG 2.30 CompactPCI® PlusIO. The new standard (a draft at present), extends CompactPCI® by PCI-Express, Ethernet, SATA/SAS and USB. It supports at the same time the PCI bus and the modern, serial, fast interconnects. It extends CompactPCI® by PCI Express and Ethernet for multiprocessing. SATA/SAS is available for building RAID hard disk systems. USB on the other hand is well suited for connecting radio modules (wireless communication like WiFi etc.). The signals are located on the user I/O pins on J2 so that CompactPCI® PlusIO can also be used on single Eurocards. 64-bit-communication on the legacy PCI bus is not possible, however.
A PICMG sub-committee is preparing CompactPCI® Plus. CompactPCI® Plus is based on the CompactPCI® PlusIO architecture, but dispenses with the PCI bus. A denser connector, which supports even higher transfer rates, permits to connect up to nine slots. No bridges or switches are needed for this. CompactPCI® Plus corresponds to the architecture of the chipsets from the mobile and server range of the next years. The PCI bus can be controlled via a system slot with double width. The CompactPCI® Plus peripheral boards are compatible with CompactPCI® PlusIO.
CompactPCI® evolves further. The architecture adapts to modern chipsets. The proven mechanics of the IEC 1101 are adopted. Existing boards can be continued to be used. CompactPCI® in conjunction with the extensions PlusIO and Plus is a future-safe platform for industrial computers.