Don’t Get Run Over: The Evolution of PC Bus Technologies

Written by: Tiger Yeh, Advantech Corporation, Industrial Automation Group

Over the last decade, there’s been an increasing trend toward the use of PC-based automation solutions. In the early 1990s large automakers and other manufacturers began using standard PCs for machine control. These systems often replaced the compact, microprocessorbased solutions – programmable logic controls or PLCs – that were found in most plants at the time. Since then, PCs running Microsoft Windows and other operating systems have worked their way into a wide variety of industrial applications, experiencing growth that outstrips competing solutions.

As a result, the guts of a PC and the evolution of those components have become ever more important in automation. Traditionally, microprocessor advances have gotten the hype, with semiconductor companies touting faster and faster clock rates in their marketing. However, storage and I/O innovations are just as vital. The latter involves bus technology, which often forms the literal and figurative backbone of a PC.

Thus PC bus technologies – past and future – are important to automation end users and the overall automation market. As for why PCs have proven so popular in industrial settings, that has nothing to do with hype and everything to do with the bottom line. For one thing, the price of PCs, whether aimed at industrial or consumer use, has fallen and continues to fall steeply. In mid-2005, for example, the world’s largest PC vendor offered a fairly capable machine for under $300. That was a 40 percent decline from the price of a similar system a year before and an even farther drop from the price of a similar system two years previous.

Another bottom line plus is that a PC-based approach often leads to substantially reduced wiring expenses and significantly fewer components. Both factors cut costs and tend to make PC-based control very attractive when compared to the alternatives.

This good price performance ratio is coupled with an open architecture. That makes innovation both easier and not dependent on the whims of a single supplier. It also means that PCs in industrial settings can benefit from hardware and software advances in the commercial arena. Consequently, PC-based automation solutions have taken advantage of changes in bus architecture over the years.

-----------