CompactPCI Serial goes full steam ahead

The popular and very successful parallel CompactPCI specification (PICMG 2.0) has enjoyed a long life and is in fact still in use today across multiple industries. Its progeny is the CompactPCI Serial standard (CPCI Serial), PICMG CPCI-S.0. It’s a serial architecture that significantly extends and enhances the best features of the earlier standard, by combining the advantages of the proven traditional CPCI with the latest high-speed data-transfer-rate technologies. A growing ecosystem is now taking this standard into some interesting applications (see sidebar).

CompactPCI Serial technology is ideal for use in systems requiring symmetrical multiprocessing and system redundancy. The highly flexible standard offers an easy-to-use and cost-optimized development and deployable environment. It provides new ways for designers to work effectively in applications that have either previously used CompactPCI or will benefit from the new platform.

The architecture retains such features as system-level management and hot swap of boards during operation, enhanced with enhanced with serial point-to-point connections and a new connector with a signal density of up to 184 pin pairs (on 3U) and transmission frequencies of 12 Gb/sec. Single-star or full-mesh topology backplanes come in up to nine slots, the max as defined by the specification, but a bridge can be added to extend the backplane.

While full details can be found at, following are some of the specific attributes of the high-speed interfaces, as well as the back-end architecture:

· Up to 8 PCI Express (6 x 4 lanes, 2 x 8 lanes)


· 8 USB 2.0/3.0

· 8 Ethernet interfaces plus signals for general system management (reset, IPMB, hot plug, geographical addressing, among others)

· 12 V (60 W per 3U slot, 120 W per 6U slot)

The system slot is positioned as the first slot and can be either on the left (typical) or the right. Each peripheral slot, all of which are simultaneously accessible, offers one PCI Express link, one SATA/SAS, and one USB 2.0/3.0 interface. The star topology is equal for all of these, and the slots are identical except for the two PCI Express x8 lanes. Defined system and peripheral slot pin assignments will allow a system slot board to plug into any peripheral slot, thus supporting symmetrical multiprocessing.

Up to eight Ethernet interfaces with transmission capabilities of 10GBASE-T and higher are also supported by each slot, building a full mesh and affording the ability to configure redundant, safety-critical systems.

High-speed connectors for fast performance

The most important factor behind CompactPCI Serial's incredible performance is its high-speed connectors. The serial point-to-point connectors are equipped with 184 signal pairs and a 3U backplane, facilitating transmission rates of up to 12 Gbps (Figure 1). The connectors are attached on four sides making them very robust, with the “female” end of the connector attached to the backplane to reduce the risk of malfunctions, even in demanding working environments; the rear I/O uses the same connectors.

Beyond this, access to WLAN can be attained via the USB hub, while powerful and rapid storage and RAID applications can be implemented through existing SATA interfaces. This technology can be effectively employed in safety, broadband-communication, and facility-automation environments. Used in transport, the technology can bring passengers greater comfort upgrades such as onboard infotainment systems and better-quality climate control.


Figure 1 | Views of CompactPCI Serial backplanes and their high-speed serial connectors.

Extended possibilities in traditional applications

CompactPCI has always been perfectly suited for use in the areas of industry and transportation. That has not changed, but with the inception of CompactPCI Serial, the ecosystem offers additional potential in the areas of transportation and defense.

· Railway: CPCI Serial made its earliest debut in railway applications. The enhanced communications protocols on a rugged Eurocard form factor lend itself well to rolling stock, trackside applications, and passenger-communications systems.

· Traffic control: CompactPCI Serial was the selected computing architecture for a speed-monitoring system for highways. The system monitors vehicles speeds; those over the set limit are photographed and their information is photo and sends to the main system for processing. The maker migrated its system from the older CompactPCI in order to increase the speed for both monitoring as well as image processing. CPCI Serial enabled the customer to simplify integration of its existing electronics and interfaces.

· Scientific research: The scientific and physics labs use a multitude of computers based on a wide range of standards. VMEbus was at one time one of the more common platforms found there. Among the newer platforms being built, CPCI Serial has been selected to replace some older VME systems because it offers the higher data rates and serial interfaces on the same mechanical form factor, making it an easier path towards next-gen system development.

The future is serial – CPCI Serial, that is

The trend is clear: Future CompactPCI applications within railway, transportation infrastructure, and some industrial automation demand high system performance and universal interfaces. New products are being designed to meet increased rugged requirements, such as conduction options.

There is a derivative specification for use of CPCI Serial in space; this includes a dual-star topology option and an open management bus for space-related communications protocols, as well as rugged and thermal enhancements needed for operation in the severe environments of space. CPCI Serial for Space is finding its way onto orbiting satellites, as one example.

A technical subcommittee, being formed as of this writing, seeks to define CompactPCI Serial extensions. The new specifications will address the need for higher speed applications including support for PCIe Gen 4/Gen 5 and Ethernet KR4.

Valerie Andrew is senior strategic marketing architect for Elma Electronic. She has spent much of her career in the embedded computing industry and led marketing and outreach initiatives for open standards trade associations including VITA, PICMG, and most recently SOSA [Sensor Open Systems Architecture]. She currently serves as an officer for PICMG. She is responsible for all communications, events, and outreach with industry partners and trade associations.

Elma Electronic ·


The growth of the CompactPCI Serial ecosystem is rapidly expanding, offering new performance and I/O options. Here is a partial list of manufacturers who offer CPCI Serial products for the ecosystem.

· Aaeon

· Acromag

· ADlink

· Advantech

· Advanced Micro Peripherals Ltd.

· Elma Electronic


· esd Electronics

· Fastwel

· Hartmann

· Heitec

· Kontron

· MEN Micro

· nVent

· Pixus

· Trenz