CompactPCI system

Thursday, 01 February 2007

CompactPCI is a standard laid forth by the PCI Industrial Manufacturers Group (PICMG) which specifies an electrical superset of desktop PCI utilizing a form factor suitable for rugged applications (e.g. industrial computers). A computer bus comprises a set of signal lines that extend in parallel between multiple peripheral connectors or "slots." Peripheral devices or expansion cards can be plugged into the peripheral connectors. Examples of such peripheral devices include memory devices, mass storage interface devices, sound cards, graphics cards, other I/O cards, etc. The PCI (Peripheral Connection Interface) bus is one popular example of a computer bus. The PCI bus is used in popular personal computers, in conjunction with a motherboard. A processor and other base components of a computer are located on the motherboard, and peripheral components are installed in PCI connectors on the motherboard to customize a computer to a particular user's requirements. The PCI bus architecture is widely employed in a variety of computer systems, ranging from desktop or notebook personal computers, to network servers. The PCI bus satisfies the needs of a personal computer, in which it finds its primary application. The PCI bus specification, however, is not well suited for industrial applications in which high reliability, redundancy or hot plugging features are very often considered as key requirements. Industrial computers are however quite different than personal computers. Due to the server environment that may be encountered in industry, industrial computers are designed to be more durable and more protected against poor environment. They often use a rack-based chassis. Peripheral components are inserted into connectors that are located on the backplane at the back of the chassis. The backplane provides a physical connection for the peripheral boards. It also provides electrical connections including power and busing. There are numerous limitations of the PCI bus Specification that make the bus impractical for industrial computers.

CompactPCI is a high level bus structure for industrial computers. The CompactPCI Specification was prepared by the PCI Industrial Computer Manufacturers Group (PICMG) to provide a standard form factor for industrial computers that employs mechanically robust connectors. The specifications thereof are consistent with that of the PCI bus standard, but its mechanical specifications are different. CompactPCI computer systems employ industry standard mechanical components and high performance connector technologies to provide an optimized system intended for rugged applications. The CompactPCI defines industry standard mechanical component and high performance connector technologies for optimized systems intended for rugged applications. A CompactPCI-based computer system is electrically compatible with the peripheral component interconnect (PCI) Specification, allowing low cost PCI components to be utilized in a mechanical form factor suited for rugged environments. The CompactPCI standard uses industry standard mechanical components and high performance connector technologies to provide an optimized system. The CompactPCI standard provides a data processing system that is electrically and mechanically compatible with the Specification. In a CompactPCI bus system, the bus is part of a powered backplane, and specialized circuit cards with staggered pins for the orderly application of power are coupled into the CompactPCI bus by insertion of the cards into slots on the backplane. The most apparent difference in the use of an interface card in a compact PCI from the use of such in a general personal computer is that the former adopts a front face connection, whereby a panel for the I/O port connector is oriented in parallel with the system bus connector. As a result, the panel of the interface card is also the panel of the machine so that the interface card is easily connected with the panel. CompactPCI bus provides a Hot Swap feature, which is the ability to plug cards into and out of the backplane in a live (powered) environment without having to turn off system power. A further feature of the CompactPCI bus is that it allows processor boards or system boards to be plugged into the bus rather than residing on a motherboard. Thus, the CompactPCI bus is usually utilized in conjunction with a passive backplane, which accepts both peripheral boards and system boards.

A CompactPCI computer system generally includes an outer chassis and a connector plane, such as a backplane board or a mid-plane board, forming various connectors and bus circuitry. A CompactPCI backplane often incorporates the CompactPCI bus segments for communication and data transfer purposes. CompactPCI backplane slots for CompactPCI boards may be implemented with one or more connectors. The CompactPCI computer system typically includes a number of other components, such as processor cards, input/output (I/O) cards, memory cards, power supplies, hard disk drives, cooling fans, etc. The chassis and the connector plane combine to define a series of slots into which PCI cards are inserted. Backplane connectors are designated as P1 through P5 corresponding in location to the CompactPCI board's connectors J1 through J5. In a CompactPCI chassis employing a mid-plane as a connector plane, both the front and back regions of the CompactPCI-based computer system are configured to load and operate the various CompactPCI cards. A CompactPCI system comprises a mechanical frame having eight CompactPCI card locations including one system slot, responsible for bus arbitration, clock distribution and reset functions for all other CompactPCI adapters on the bus, and up to seven Peripheral Slots that may contain adapters, PCI slaves or PCI bus masters. Each CompactPCI card is connected to the connector plane by a set of connector pins. Connection of the CompactPCI card to the connector plane therefore requires a substantial insertion force, and a corresponding substantial extraction force, upon removal.

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