November 1997

BY SUZANNE M. LOACH

Computer technology is evolving so quickly, we tend to forget how recently the PC/XT and its 4.77MHz processor were considered state-of-the art. With CPU speeds now pushing 600MHz and with parallel gains in memory, mass storage, software, and every other aspect of the technology, consumers are increasingly hard-pressed to make informed decisions about which hardware elements to buy. This problem is underscored by the fact that CTI is the hottest growth niche for PC technology today, which makes the job of trying to balance today’s system needs against those of tomorrow even more difficult. It is in this context that we will explore how the passivebackplane industrial PC form factor enhances system reliability and scalability, with an eye toward providing developers, integrators, and users with knowledge to help them configure their CTI hardware platforms more efficiently.

By the mid-1980s, office PC technology had migrated to the industrial factory floor, where users began to exploit its tremendous potential for data acquisition, measurement, and control. Despite its speed, computational power, and lots of compatible hardware and software, the office PC suffered high system-failure rates due to the harshness of the industrial environment. In response, ruggedized designs based on the IBM PC bus architecture soon appeared with features that allowed them to operate reliably in the heat, humidity, dust, and vibration that had previously caused users headaches and downtime.

The success of the ruggedized PC format quickly led to such diversity of use that the term “industrial” was broadened to include any mission-critical application where downtime was to be avoided. Thus, whether it may be for industrial process control, downloading a network feed of the evening news, or for a sophisticated interactive voice response application, industrial PCs exhibit certain common features. These features might include:

• Chassis made of EMI/RFI (electromagnetic interference/radio frequency inter-ference)resistant steel instead of plastic.
• Powered by a single-board, plugin CPU with a higher MTBF (mean time between failure) than activebackplane (motherboard) CPUs.
• Watchdog timer for automatic reset or alarm in the event of a system lockup.
• Multiple fans and filters utilize positive pressurization resulting in better cooling of the CPU and other chassis “hot spots.”
• Redundant N+1 power supplies for load sharing and fault tolerance.
• Hot-swappable power supplies, drives, and other components.
• Shock- and vibration-damped drives and other fragile components.
• Hold-down clamp to secure feature cards and ensure firm board connections.
• Strain relief to keep tension off cords, cables, and connectors.
• Lockable access to control switches and keyboard/mouse ports to prevent unauthorized system entry.
• Agency approvals (UL, c-UL, CE, etc.) to ensure quality and safety compliance.
• Vertically stacked installation in a 19-inch or 23-inch rack cabinet for minimum space usage.

PASSIVE BACKPLANE VERSUS MOTHERBOARD
The basic differences between these two bus architectures strongly impact the overall reliability and scalability of the PC platform. The motherboard is the main system board on which are mounted the CPU, connectors, adapters, serial ports, timing circuits, and all other active components required for system operation. In contrast, the highly modular, passive-backplane architecture includes absolute minimum numbers of components on the backplane. Instead, the CPU, serial ports, floppy controllers, and all of the other system components are provided on individual plugin boards which are easily installed into slots in the computer backplane. Though still quite popular, motherboard systems have been largely superseded by passive backplane technology for high-availability systems due to:

• Intrinsically lower MTTR (mean time to repair or replace) singleboard computers can be swapped in less than five minutes without disconnecting the system wiring connections.
• Passive backplane technology offers greater expansion capability, with some vendors’ chassis providing up to 20 expansion slots.
• Superior thermal management demanded by the new generation of high-performance CPUs.
• System compatibility allows users to upgrade their 386/SX, 486, and Pentium single-board CPUs without having to disconnect the system wiring or buy a whole new system. Motherboards are generally less expensive but with only eight expansion slots typically available, they are somewhat less flexible. Most newer motherboards are incorporating fewer of the ISA bus connectors for expansion, limiting their use for most legacy feature cards used in the industrial market.

When problems occur, motherboard systems are often highly laborintensive and therefore costly to repair. The system frequently must be dismantled to get at the problem, or the entire computer must be replaced. Typical problems that CTI developers may experience with motherboards include incompatible BIOS, inability to handle high interrupt loads, and sensitivity to bus noise. On the other hand, motherboard systems can be an advantage to the small system user who has no current or anticipated need to expand the present system platform. However, the lower initial cost benefit of the motherboard system soon evaporates if a costly repair or system replacement is required. Keep in mind that most low-cost, offshore-manufactured motherboards are produced in very high quantity lots one time only, which means a replacement board ordered six months or six weeks later may have a totally different layout or BIOS.

Alternatively, U.S.-made motherboards typically offer longer availability and consistency of supply but are becoming increasingly difficult to obtain. Further, CPU upgrades in active backplane systems usually require replacing the whole motherboard and many of the associated peripheral controllers. Therefore, the prime considerations to remember when contemplating the purchase of an industrial PC system include:

• Cost: Rugged PCs are initially more expensive because of costlier, more robust components, redundant fans and filters, EMI/RFI shielding, tighter specs, and other factors which boost the cost of manufacture.
• Reliability: A fully ruggedized industrial PC system should be good for 100,000 to 150,000 poweron hours (POH) versus 15,000 to 30,000 POH for a good quality office-style clone. Extra cooling and filtration dissipate excess heat, which adds significantly to component life.
• Serviceability: The passive-backplane bus structure allows major system components, including power supplies, feature cards, and even the CPU to be replaced in 5 minutes or less.
• Expansion Slots: Passive backplanes provide up to 20 board expansion slots versus a maximum of 8 for most motherboard systems.
• Upgradeability: The industrial PC’s intrinsic compatibility from one revision to the next allows users to upgrade their 486 or Pentium plugin CPU boards for use with their existing passive backplanes without having to disconnect their system wiring or buy a new system.
• Cooling And Filtration: The main cause of premature component failure is the heat generated by cardintensive applications. A 20slot industrial computer chassis can compensate for this by augmenting its natural convection cooling with multiple high-cfm (cubic feet per minute) cooling fans that eliminate any hot spots in the enclosure.
• Mounting: Space-effective 19inch racks allow easy mounting and quick access to as many as eight industrial chassis in the same enclosure. For applications requiring many input/output channels or a very large number of feature cards, drives, RAID (redundant array of inexpensive drives) data storage subsystems, and the like, rack systems are the ideal solution.
• Noise Rejection: Steel enclosures are not only better at filtering out RFI/EMI to prevent loss or disruption of data, they also provide better grounding.

PICMG-COMPLIANT BACKPLANES
The PICMG industrial standard was created with the formation of the PCI Industrial Computer Manufacturers Group. Now with about 300 member companies, PICMG provides a broad-based open architecture to ensure interoperability with other standards, including existing ISA designs.

This was accomplished in part by adding a PCI connector to existing ISA CPU boards, which in effect precluded the need to redesign the entire edge connector. In this way, a two-step migration approach was provided for OEMs and users wishing to upgrade to PCI performance. One approach is to run a PCI sin-gleboard computer in the existing pas-sive ISA backplane and achieve performance improvements on the CPU card. A second approach is to replace the backplane or system chassis with a PCI industrial standard backplane and translate that performance improvement to the bus.

As with ISA standard passive backplanes, PCI backplanes can accept a wealth of readily available adapter and feature cards, which may be either ISA or PCI bus cards. Offering the capability of both buses on a single backplane provides the widest possible choice of adapter cards for any application. The PCI bus portion of the backplane offers as much as 132MB/sec of throughput, depending on the processor chipset, clock rates, and the like.

In terms of scalability, the ISA/PCI backplane also offers both backward and forward compatibility. The ISA bus still runs at 8.33MHz, thus insuring compatibility with all previous levels of ISA bus adapter cards. The PCI bus runs at the 32MHz specification and is fully PCI-compliant, enabling it to handle today’s adapter cards and providing the capability to accommodate tomorrow’s as well. Although 64-bit technology is still in its infancy, interest is growing.

The CompactPCI specification — in addition to PICMG passive backplanes — will be able to handle 64-bit technology as the need for it develops and as adapter and feature cards and operating systems become available for it. It is worth noting that not all ISA/PCI backplanes are designed, manufactured, or tested to PICMG specifications. For example, several backplanes are now being advertised with spare CPU slots.

There is no such thing in the PICMG specification. In general, these backplanes tend to have exceedingly long circuit traces, quite likely exceeding the maximum allowed by PCI specifications. They also tend to have four expansion slots (in addition to the CPU and “spare CPU” slot) which seem to exceed PCI specifications for the maximum number of loads on the bus. In order for the backplane to have a chance to be compliant, the CPU board may not have more than one PCI load (controller) on board. The point is, before purchasing an ISA/PCI backplane, verify that the manufacturer is a member of the PICMG consortium and is following the proper guidelines.

PLUG-IN SBCs
Some Pentium single-board computers (SBCs) allow both ISA and PCI bus operations together, with all of the necessary high-performance hardware peripherals residing on the board itself. For example, on the PCI bus, the 2940compatible SCSI controller and fast and fast/wide SCSI-2 devices operate at 30MHz processing versus 8.33MHz on the ISA bus. The video chip and the enhanced IDE hard drive controller are also on the PCI bus, which allows users to take advantage of the dramatic increases in I/O throughput speed that PCI offers. EIDE drives can provide up to 16MB/sec throughput and performance is being accelerated by all manufacturers. The ultra wide SCSI controller now supports throughput rates of up to 40MB/sec.

The benefits of higher throughput, however, can only realized if the SBC’s onboard controllers are able to optimize the high-performance peripheral. Otherwise, it becomes much like driving a race car in heavy traffic. Any high-performance SBC should include, as a minimum, the following onboard peripherals: EIDE controller, dual serial ports, and a parallel port. Optionally, the SBC may also include the video controller and SCSI controller.

Advantages of this include: consistency of supply of video controller, agency approval of the SBC covering the video and drive controllers, and compatibility between these system components. Tremendous performance advantages affecting throughput, peripheral access times, data transfer rates, and other important parameters may be gained by upgrading the CPU to a higher level in order to maximize the system’s expandability potential (Table 1). This upgrade may be accomplished easily by plugging a new CPU into an existing passive backplane, taking advantage of the intrinsic flexibility of that particular form factor from one revision to the next. Since most higher performance, single-board CPUs provide expandable cache RAM, PCI local bus video, and SCSI-2 and EIDE drive controllers onboard, upward compatibility is assured, and the need for separate addon controller cards is eliminated.

As far as the newer Intel processors are concerned, Pentium II may require some substantial changes in industrial systems, especially in the PICMG and CompactPCI products, to insure proper mounting to handle vibration and shock. The Pentium II is a significantly different package in what Intel calls a Single-Edge Connector Cartridge or SECC. The SECC plugs into a slot on the motherboard, similar to a feature card slot, but it is definitely unlike the processor sockets that were used with 80386, 486, and 586 technology. This SECC will change the way passive backplane systems will be built from now on, and there may well be limited backward compatibility for SBCs.

CT STANDARDS EVOLUTION
The Enterprise Computer Telephony Forum (ECTF) is driving the adoption of a new software and hardware CT Bus interoperability standard known on the hardware side as H.100. The specification’s emergence coincides nicely with the industry’s continuing migration from ISA to PCI technology. The major proponents of the two leading proprietary CT buses, SCBus and MVIP-90, are leading the charge towards the universal bus standard.

H.100, the first board-level definition of the overall CT Bus single-communications bus specification, allows developers to implement a CT bus interface at the physical layer of the PCI computer chassis card slot, independent of software applications. This will allow H.100-compliant PCI products to interoperate with others in the new CT Bus core mode and simultaneously with SCBus and MVIP-90 or HMVIP using CT Bus compatibility modes.

While H.100 is designed for PCI form factor boards, it interoperates easily with existing telecom buses on existing ISA/EISA PC boards and can therefore work in any computer chassis, including those with both PCI and ISA slots. The ability to mix older bus products with developing H.100-compliant products ensures future expandability by eliminating the need to replace an existing system. Development is also underway on H.110, an equivalent hardware specification for CompactPCI.

CONCLUSION
Because it is moving with such speed and momentum, the worldwide CTI market is simply too dynamic to accurately gauge at present. Industry estimates are all over the board as to its current and projected size. Figures recently obtained on the Internet range from $3.5 to $6.4 billion annually, with growth rates anywhere from 19 percent on the low end to 100 percent in certain sectors. IVR, fax-on-demand, and voice mail, for example, are quoted by one Cambridge, MA-based group to be growing at 30 percent per year. The same source also claims that by the year 2000, the technology sector of the Internet will be over $14 billion annually, up 1,200 percent from just five years before.

One thing is clear: In explosivegrowth markets like CTI, product life cycles will continue to be shorter as newer, better solutions come and go. This makes the job of hedging the hardware platform more difficult and can blur the distinction between investing in the future and designing disposable systems. However, the emergence of compatible hardware standards like PCI, CompactPCI, and H.100, driven by industry-wide organizations like PICMG and ECTF, will continue to evolve with the market and provide viable guidelines for reaching the next level. In terms of the hardware platforms that will run these increasingly sophisticated CT applications, the passive backplane industrial PC will most likely continue — for the foreseeable future — to offer the most cost-effective, reliable, and workable migration path to future PC-based technology.

Suzanne M. Loach is Product Manager at Industrial Computer Source, a company that manufactures and stocks PCbased 486 , Pentium , Pentium I Motherboards, Pentium Pro and Alphabased computer systems, data acquisition, communication, networking, and computer telephony products. These product families are targeted for the industrial, scientific, and telecommunications marketplace. Industrial Computer Source manufactures and sells PC-based products to the universe of engineers, scientists, and other technical users. These professionals oversee industrial automation, computer telephony, data acquisition, laboratory research, and process control projects. For more information, visit the company’s Web site at www.indcompsrc.com.

Last year, a major U.S. telecom carrier contracted Industrial Computer Source to design and build a number of fully integrated 48VDC computertelephony systems for export to a joint venture partner in Mexico. Since then, over 60 complete rack systems have been installed for longdistance switching and advanced fiberoptic telecommunications network control and management in cities throughout Mexico. This application represented the entry of sophisticated CTI, including Internet access, multifax, callingcard, and 800 service, to the emerging Mexican market with its potential customer base of 94 million users.

Mission-critical telephony applications like this rely on high reliability systems, and nowhere is this experienced more acutely than outside the United States, where operational conditions can be a real challenge. To meet the needs of this particular application, the custom 19” rackmount platform included a number of industrial-grade refinements. Chief among these were the Global Interference Reduction System. The GIRSystem is a unique electrical noise mitigation technique stemming from a mechanical design improvement to the PC chassis which enabled it to be certified CE compliant. Other ruggedized system elements included multiple fans, filters, and shockmounting for the drives and boards to protect the system from damage caused by occasional seismic activity at the point of use.

Within the last two years, exporters of electronic systems have felt tightened regulatory requirements relative to the discharge of, and susceptibility to, electromagnetic and radio frequency interference, or EMI/RFI. Hardware manufacturers have tried Chassis Improvement Yields Lower EMI/RFI At Faster CPU Speeds many ways — some at the board level and others at the chassis level — to solve the nagging electrical noise problem, which became more pronounced as CPU and bus speeds climbed. The GIRSystem was designed by Industrial Computer Source as a system-level solution to eliminate the EMI/RFI emission and static discharge sensitivity problems associated with today’s ultra-highspeed computer systems which will soon exceed 600MHz.

While “quiet” processor boards may be designed and employed, the system chassis still needs to contain the emissions of the feature cards used by the application. The GIRSystem solution involved modifying elements of the chassis itself to accommodate the much shorter wavelengths and to compensate for leakage paths that were unknown with the original 5MHz XT and 8MHz AT designs. These mechanical design improvements included the addition of:

• RFI gasketing to seal the top of the chassis.
• Tightened weldments to improve chassis integrity.
• Well-grounded front panel access doors to disk drives.
• Reduction in leakage paths during the chassis fabrication process.
• A new RFI leakproof design for the mounting of adapter cards.

The original XT design card mounting bracket had never been upgraded nor had any significant change been made to the way the brackets were grounded. As processor speeds increased, the typically long interface between the card mounting bracket, backplane, and the chassis became a cavernous avenue for RFI leakage and the chassis’ weakest link as a source of electrical noise emissions. The fix involved adding a gasketed bracket guide which provided a full-length RFI seal that effectively closed the gap without impairing the installability of ISA/EISA bus based PC adapter cards. This electrical noise mitigation technique satisfies the 89/336/EEC directive for CE mark now required in Europe and, as a point of reference, is more stringent than FCC Class B for both emissions and susceptibility. Compliance was verified through laboratory tests using both 300MHz Alpha and 200MHz Pentium-based systems.

Industrial rackmount chassis employing the GIRSystem may be used in any application requiring the newest processors in high-noise environments or in applications sensitive to emissions from the system. Several popular passive backplane bus options, including a hybrid backplane combining active elements with a passive backplanestyle architecture, are configurable. Further, the ability to segment the passive backplane into as many as five, fully autonomous “computers within a computer” greatly increases the utility of the server platform by optimizing its scalability as a hedge against obsolescence as future needs evolve. The passive backplane architecture concept has been validated by the 300 member PCI Industrial Computer Manufacturers Group and is now considered to be the industry standard for industrial PC systems.

Open Solution For Leading Paging Company

BY PAUL THOLE

A large paging company was in need of open architecture computer telephony platforms. This particular paging company — the sixth largest such company in the world — is among the fastest-growing paging companies, providing service to more than 2 million subscribers in over 1,200 U.S. communities in all 50 states, Canada, Puerto Rico, the Virgin Islands, and the Bahamas.

THE NEED
The paging industry is highly competitive. Many paging companies differentiate their offerings through a variety of enhanced services — voice mail, information services, and the like. These enhanced services are typically in the form of proprietary turnkey computer-telephony solutions, sourced by third-party vendors. Because of the proprietary nature of these solutions, and the fact that they are sourced outside the company, the paging company was having a difficult time developing and bringing new enhanced services to market quickly. The proprietary system providers typically provide a 6- to 12-month turnaround on new applications. The paging company’s goal was to be able to take an enhanced services application from idea, to proof of concept, to deployment in less than 90 days.

THE SOLUTION
The paging company decided to develop their own enhanced service applications, and deploy them using an “open” systems computer telephony platform. They chose Alliance Systems, Inc., to provide the necessary hardware and integration ser-vices. The Alliant computer-telephony server, a fault-tolerant platform with hot-swappable components, was integrated with AG-T1 cards from Natural MicroSystems. The total integrated solution included:

• A total of seven Industrial grade, rack mount CT platforms. Each server included a 20-slot passive backplane, Pentium 200 singleboard computer, 64 to 128 MB of RAM, and a 9.1-gig Seagate Cheetah (10,000 rpm) SCSI hard disk drive. Each chassis also included redundant, hotswap power supplies, and three cooling fans. All redundant components, including power supplies, cooling fans, and hard disk drives, were hot-swappable, and monitored via a “smart chassis” alarming function. In the case of a component failure, visual and audible alarms are invoked. Additionally, in the case of a cooling fan failure, or rise in internal chassis temperature, the system automatically increases the CFM output of the cooling fans, in order to compensate.
• The system also included an industrial grade, rack mount, hard drive enclosure, containing a total of four SCSI hard drives. This was configured in a RAID 5 hard disk array, with three 9.1-gig drives providing a total of 18 gigs of RAID storage. Additionally, a 9.1-gig hot spare was included for enhanced fault tolerance. In the case of a hard drive failure, the hot spare automatically replaces the failed drive.
• Windows NT Server 4.0 was selected as the operating system for all chassis. The total solution was configured as a domain with one primary domain controller, two back-up domain controllers, and four stand-alone servers.

Alliance integration specialists integrated and tested all of the components including the hardware, operating system, drivers for the Natural MicroSystems AG-T1 cards, and telephony components. Finally, all integrated servers were mounted in an industrial, 7-foot rack. By deploying an open solution, the paging company was able to shorten the development cycle dramatically, in some cases to as little as 30 days.

Paul Thole is a marketing manager at Alliance Systems, Inc., a respected leader in computer telephony systems integration with over 5,000 customers worldwide. Its technology division designs, builds, and tests industrial grade computer telephony systems of any size. Services include system configuration and design, integration and staging, outsourcing, and postsale technical support.