Compact PCI Serial provides serial interfaces between the different modules in the system vs. the parallel bus as provided by the existing CompactPCI. CompactPCI Serial (PICMG CPCI-S.0) is consistently based on the mechanics of CompactPCI (PICMG 2.0), so it remains 100% compatible to IEC 1101 (defining the mechanical form factors). Only the connector is replaced by a new type which is able to support the high frequencies of 12 Gb/s and more. A system can support a multitude of serial busses at the same time to support different functionalities: a total of six PCI Express links with up to four lanes each, two links with up to 8 lanes, all for high speed communication between modules, eight SATA/SAS interfaces for mass storage devices, eight USB 2.0 as well as eight USB 3.0 for intelligent modules, eight Ethernet interfaces for standard communication, and a number of signals for supporting these interfaces and for general system management.

CompactPCI Serial is compliant with the 19” mechanics of the IEC 1101. It defines a new connector for the serial interconnects with higher speed and more pins that cannot be used on a PICMG 2.0 backplane. The dimensions of the backplanes are identical to those of the CompactPCI backplanes and are fixed in the same way. Front panels and handles have not been changed either. The well-proven hot plug mechanics – the switch in the handle – remains the same. CompactPCI Serial is interoperable with CompactPCI in the same system.

• Proven mechanical form factor with serial interconnect
• Star topology with USB, SATA and PCI Express (connecting up to 8 peripheral cards)
• Full Ethernet mesh with up to 9 cards
• 19” mechanics (IEC 1101) as known from CompactPCI (or VMEbus)
• 3U and 6U cards on a passive backplane supporting exclusively serial interconnects
• Up to 9 cards per system without switches and bridges (more than 9 slots with bridge)
• Same CPU card can be system or peripheral slot in a system
• All peripheral cards can be plugged in any of the peripheral slots

The standard has defined the AirMax connectors from FCI. A second source is Amphenol TCS.

3U and 6U – the two formats are electrically and mechanically compatible. 3U boards can also be inserted into 6U systems without restrictions because connector types and pin assignment are identical. The only difference is that for 6U boards an optional connector (P0) was added to amplify power supply and to provide additional Ethernet channels as an infrastructure bus for server applications.

3U boards are not inserted at the bottom, as for (parallel) CompactPCI, but at the top, meaning that 3U boards are supplied via the so-called P1 connector. For 6U, this connector needs to be extended. For EMC reasons and in order not to influence data transfer on the serial interconnects, the power supply connections have as large a distance as possible to the critical signal paths. Thus the P0 connector is directly placed below P1, which makes the board grow “towards the bottom” (for vertically mounted miodules).

As the parallel CompactPCI bus, also CompactPCI Serial is truly a "systems level" bus, with configuration (plug and play) and hardware abstraction layers. This permits a high level of software portability, common in the desktop PC world but much rarer in embedded systems. This means in practice that all software common to the office PCs can run without change on these systems.

Yes – the CompactPCI Serial specification is upward-compatible to next generation PCI Express, USB 3.0 and 10 Gbit Ethernet. And SATA is only dependent on the on-board features of the CPU card.

There is currently no workgroup planned beyond the one for CompactPCI Serial. We might expect to see, however, a series of design guides to describe the multitude of possibilities of building and designing hybrid solutions on system level as well as on board level – including CompactPCI Express, VMEbus, VPX, VXS.

VITA 46 VPX is also based on 19-inch technology and is used increasingly in military applications. VPX supports various high-speed interfaces, but not simultaneously. For this VPX defines boards and slot spacings for the different environmental conditions of air cooling through conduction cooling to direct liquid cooling of hot-spots on the board, which can dissipate up to about 450 watts.

MicroTCA uses a new mechanical system, and so a soft migration is considerably more problematic. Its extensive shelf management and hot-swap capabilities are core: functionality, power and cooling requirements are checked before the board is powered up. Remote maintenance is implemented in the shelf management. MicroTCA supports a wide variety of high-speed interfaces, which results in restrictions on simultaneous availability in the system.