CompactPCI expands the reach
of the PCI bus
The architecture's high speed and rugged specification are designed to meet
system performance and reliability requirements well into the next decade
BY JOE PAVLAT
Pro-Log Corp.
Monterey, CA
A new offshoot of the Peripheral Component Interconnect (PCI) interface is fast
becoming the next open bus architecture for industrial and telephony
applications. Developed under the auspices of the PCI Industrial Computer
Manufacturer's Group (PICMG) and named CompactPCI, the architecture came about
as a result of ever-increasing demand for more bandwidth, higher performance,
ruggedness, and lower cost in industrial and scientific applications.
Key to CompactPCI's acceptance is its close ties, through PCI, to the
ubiquitous desktop PC. With more than 40-million PCs sold annually, PCI bus
volume has reduced component costs to a minimum. PCI's acceptance goes beyond
the PC, however. Motorola, IBM, Digital Equipment Corp., and Apple
Computer–Intel competitors–have incorporated PCI bus into the PowerPC,
Digital's Alpha-based computers, and the Power Mac.
With a typical throughput of 80 Mbytes/s at 32 bits and 33 MHz, CompactPCI has
20 times the equivalent throughput of ISA bus and four times the throughput of
VMEbus. Such throughput is essential for such demanding applications as
high-speed data acquisition, voice recognition, and vision systems.
With respect to ruggedness, CompactPCI uses the Eurocard form factor, which is
similar to VMEbus in both 3U and 6U formats. The vertical orientation of
CompactPCI's backplane mounting allows for convection cooling, thus allowing
CompactPCI systems to work in a higher ambient temperature than a desktop PC.
Also, the architecture's indirect pin-in-socket connector makes the connection
more secure and immune to vibration, shock, and even corrosive environmental
conditions.
Flexibility
A cursory examination of the PC motherboard reveals that it is insufficient to
meet the operating needs of many classes of computer applications, especially
where expansion is a necessity. Because of the poor high-frequency
characteristics of edgecard connectors, only four PCI slots are available.
A major design advantage of CompactPCI is its ability to accommodate up to
eight pc boards in one card cage without requiring an expansion bridge or
degrading system performance. This makes it attractive to many data
acquisition, server, industrial, and telephone applications, which often need
to add peripherals and devices. Also, with the growing popularity of PC-based
Man-Machine Interface (MMI) applications on the factory floor, a CompactPCI
rack-mount system will allow users to integrate MMI directly into its control
system.
While it is possible to use a PCI-to-PCI bridge to extend the number of PCI
slots in a desktop computer system, the result may be awkward in terms of chip
placement and board orientation within the computer box. With a CompactPCI
backplane, if a system design requires more than eight slots, it is just a
matter of adding bridge chips to expand the bus. CompactPCI can also be
combined with other bus architectures–including ISA, EISA, and VME–to
complement and enhance system performance.
Shortened repair time
Both industrial and telecommunications users must balance state-of-the art
technology with a low mean time to repair. Lost production time in a factory
resulting from the effort to disassemble the PC, replace a board, and
reassemble the box can take half an hour, costing hundreds or thousands of
times more than the replacement part.
A passive-backplane system like CompactPCI allows users to walk up to the front
of the card cage, pull a card, and immediately insert a replacement. In
addition, because the CompactPCI P2 connector on a 6U Eurocard board has an
open definition, designers can decide where to place I/O connections.
For example, many users prefer access to I/O ports from the front, such as in
an industrial application. Here, a rack-mount system allows users to access I/O
points and replace cards from the front of the control panel cabinet.
CompactPCI also allows designers to mount I/O so it can be accessed from the
rear. Users in the telephony industry prefer mounting I/O at the rear of the
backplane system.
Many of the 116 members of PICMG are planning to develop CompactPCI-related
products. To date, three companies–Pro-Log, Ziatech, and Gespac–have
introduced and are shipping complete product lines. Several other companies
have introduced, or are planning to introduce, individual products (see box).
Pro-Log's Model 810 CompactPCI chassis (see Fig. 1) is designed specifically
for the new CompactPCI standard. These panel-mountable enclosures provide space
for up to two hot-swappable power supply modules (such as the company's Model
8920, which is $395 each), two 6U CompactPCI slots (one of which is for the
company's $2,995 Model 8876 Pentium CPU), and six 3U CompactPCI expansion slots
(for video and networking). The 810 is convection cooled, although an optional
fan module allows use in ambient temperature environments above 55degreesC. The
Model 810 chassis has a single-unit price of $1,495.
Ziatech has recently added the first fast and wide SCSI interface to its
arsenal of CompactPCI products (see Fig. 2). Called the ZT6620, the interface
is based on Adaptec RISC technology and allows for SCSI data transfers at up to
20 Mbytes/s. The board has two 16-bit SCSI-3 and one 8-bit SCSI-2 connectors.
Its single-unit price is $495.
Another recent introduction, from Alphi Technology (Tempe, AZ), offers a
complete solution for high-performance closed-loop control applications. Called
the CPCI-DSC31 digital servo controller module, the 3U board supports PID
loop-closure frame rates of up to 4 kHz/channel. The host can program
proportional gain, integral gain, derivative gain, and integration limit.
CAPTIONS:
Fig. 1. The Model 810 CompactPCI chassis provides space for up to two
hot-swappable power supply modules, two 6U CompactPCI slots (CPU plus one
other) and six 3U CompactPCI expansion slots.
Fig. 2. The ZT6620 fast and wide SCSI controller is based on Adaptec RISC
technology and allows for SCSI data transfers at up to 20 Mbytes/s.
BOX:
Manufacturers of CompactPCI products
The following companies make CompactPCI products. For more information, call
the contact or circle the appropriate reader service number.
Alphi Technology Corp.
Tempe, AZ
Mark Stephens 602-838-2428
Fax 602-838-4477
info@alphitech.com
A/D and D/A converters, digital servo controllers, intelligent DSP boards
CES
Geneva, Switzerland
Sales Dept. 41-22-792-5745
Fax 41-22-792-5748
PowerPC boards
Force Computers Inc.
San Jose, CA
Steven Little 408-369-6232
Hybrid VME/CompactPCI boards
Gespac, Inc.
Mesa, AZ
Cosmo Pabouctsidis 602-962-5559
Fax 602-962-5750
Boards and chassis
Greenspring Computers
Menlo Park, CA
Kim Rubin 415-327-1200
Fax 415-327-3808
IndustryPack interface cards
Hybricon Corp.
Ayer, MA
Sales Dept. 508-772-5422
Fax 508-772-2963
Chassis and backplanes
Pro-Log Corp.
Monterey, CA
Sales Dept. 800-252-EASY
Fax 408-646-3517
http://www.prolog.com
Boards and chassis
Rittal Corp.
Springfield, OH
Sales Dept. 800-477-4000
Fax 513-390-5599
Chassis
Vector Electronic Co.
Sylmar, CA
Sales Dept. 818-365-9661
Fax 818-365-5718
Chassis and backplanes
Ziatech Corp.
San Luis Obispo, CA
Sales Dept. 805-541-0488
Fax 805-541-5088
http://www.ziatech.com
Boards and chassis
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