A CompactPCI (cPCI) system is a 3U or 6U (”U” is a unit of measurement of the height of a rack-mounted device, with one rack unit, or RU, equaling 1.75″) Eurocard-based industrial computer which has all of its boards joined by way of a passive PCI (Peripheral Component Interconnect) backplane. The pin assignments of the connectors are documented in standards, published by the organization PICMG U.S. and PICMG Europe (PICMG means “PCI Industrial Computers Manufacturers Group”).
The connectors and the electrical rules enable eight boards in a PCI segment. Multiple segments are allowed with bridges. (A Eurocard is a European standard format for PCBs–insulated boards on which interconnected circuits and components such as microchips are mounted or etched–which can be connected together into a standardized sub-rack.)
Yes, that’s a mouthful. More simply put, cPCI systems were originally created to be industrial buses with an extremely high bandwidth for multiple computerized applications including telecommunications, computer-to-computer communications, real-time machine control and data acquisition, industrial automation, instrumentation, and military systems. The CompactPCI system facilitates high speed computing, modular and robust packaging design, and long term manufacturer’s support.
Norbert Hauser, Vice President Marketing at Kontron, says of the Kontron ITC-320 series of cPCI systems, “[This system] is an ideal product for upgrading existing compact-sized embedded computers to a state-of-the-art processing unit with PCI-Express connectivity on the backplane.” CompactPCI is positively the wave of the future as well as the present for industrial applications, and it’s a system that’s rapidly being expanded. According to a recent press release from the European PICMG, that group has “formed a technical subcommittee to extend the current CompactPCI standard for both the 3U and 6U form factors, mainly for applications in industry, avionics, transportation, medical and in telecommunications systems that use cPCI”
The current CompactPCI standard lacks support for inter-operation with serial busses such as PCI Express, Ethernet, SATA/ SAS and USB at the backplane. CompactPCI Express with support for PCI Express has no rear I/O and there is no cost-effective migration path from CompactPCI without bridge slots. Its proposers intend that this extension will not require switched fabrics, and there is not intention to define them.
The core idea is to define a new peripheral slot supporting PCI Express as well as SATA/SAS, USB and Ethernet. Such slots can be used for PCI Express expansions (for example), but also for hard disc RAID arrays, Ethernet switches, or USB-based WiFi solutions; all modern busses would be supported on each peripheral board. A star architecture will be used to connect the system slot to the peripheral slots.