Compared with the current proliferation of more than a dozen different computer on modules (COM) concepts, CompactPCI and CompactPCI Express are founded on solid, and worldwide accepted standards that are observed by more than 100 manufacturers.
The initial COM specification of 2002 was originally drafted to enable custom-specific motherboards to host a standardised plug-in processor core that could be simply exchanged as more performance or alternatives from other manufacturers became available. This process would then permit the peripheral carrying motherboard to be kept unaltered, and the engineering time associated with processor core development minimised, so that a price optimised final assembly would result. However, as more peripheral functionality (eg SATA, USB2.0, FireWire and LPC) became available already integrated in the chipsets, the number and diversity of interface connectors increased, and with it the number of COM variants to provide support of these new features. Ultimately, new motherboards have to be developed. For this reason, many manufacturers of these COM variants offer ‘comprehensive, personalised design-in support’, which may well be a source of auxiliary income for the manufacturer, but it deviates wildly from the initial goal: the long-term supply of standardised and readily scalable processor cores.
The technical strength behind CompactPCI lies in its strict standardised CPU concept, and mature cooling concept, which guarantee a migration path for future development while ensuring long term availability. Thanks to its modular construction based on a passive backplane architecture, there is no question as to the ease of maintenance, and exchanging boards becomes a simple affair. Should an industrial PC fail, then the problem is system level as the entire unit has to be detached from cables and interconnects. The 3U CompactPCI solution by contrast, requires just the defect board to be pulled. The MTTR in such cases is kept to an absolute minimum – an obvious advantage for mission critical applications.
When considering the small, yet typical 0°C to 50°C operational temperature spectrum of the standard industrial PC or customised COM solution, CompactPCI scores additional points as a broader 0°C to 70°C is standard, and that range can even be scaled to suit even -40°C to 85°C requirements. Here, it’s the elaborate cooling concepts of the motherboard solutions that impede cooling refinements, which unlike CompactPCI, cannot keep pace with the rapidly changing developments prevalent in today’s processor architectures and features.
Even today, some COM boards based on the Pentium M processor from Intel have not yet left the design table whereas the 3U CompactPCI counterpart has been actively serving the market for years. In addition, the majority of CompactPCI CPUs are furnished, as standard, with a CompactFlash socket for solid state devices for diskless and safe operation in rugged environments. The reduced real estate of the typical COM or similar ‘modular’ solution presents the integrator with an obvious problem.
Table 1 provides a detailed comparative overview of the technologies typically prevalent in the embedded market for mainstream applications.
The development of the EcoMAX 3U CompactCPI system (Fig.1) considered all the requirements expressed of a volume-orientated embedded market segment. A major focal point being a production-optimised, economical system design that hosted the EcoCOM CPU for OEM quantities. The CPU itself is based around the industry-recognised 600 MHz ULV Celeron processor from Intel, complete with 256MB soldered memory for enhanced mechanical integrity. The complete EcoMAX system, which comprises a four-slot passive backplane, pluggable PSU, and state-of-the-art CPU complete with Linux or Embedded Windows XP as an option – is all contained within a 30HP EMI shielded enclosure.
The EcoMAX system supports all the necessary peripherals without the need for any additional boards since the EcoCOM CPU has all the functionality already built-in. Besides the USB2.0 interface, the EcoCOM is equipped with dual Fast Ethernet ports for rapid IT-network integration, and UXGA graphics. The operating system boots from a 512MB solid-state CompactFlash device for superior reliability, enhanced stability, and unsurpassed up-time, since the CPU is freed of all rotating parts. Also, the EcoMAX operates in a broad 0°C to 70°C temperature spectrum, and is practically free of EMI emissions – a plus point when considering integration costs. COM solutions, with their customised enclosures have to go through the costly, and
time-consuming EMI re-certification process each time a change is made.
New investments in engineering and production have finally enabled 3U CompactPCI systems to compete, on level ground, with COM-based alternatives – and deliver more into the bargain. The typical target applications for the EcoMAX family are in operator terminals,
point-of-sales (POS) systems, transportation, building and industrial automation. u
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Andrew Brown is with Inova GmbH, Kaufbeuren, Germany. www.inova-computers.de
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