LETTERS

Just a computer

Bêla Lipták's article on archaic control systems (InTech's April 2005 Industry View) struck a chord with me for a simple reason. I worked as a control engineer during the 1980s and 1990s and understood the proper application and maintenance of some of these systems he described. Somewhere around the year 2000, most companies decided having someone on staff that knew basic instrumentation and understood the reason for standards and the like was a luxury, so many of us gof'cast to the wind" to find other jobs. Most of these jobs are outside of our expertise, but you've got to eat! Personally, I ended up in a combined cycle power plant under construction as a Maintenance Engineer. During construction, I saw many mistakes made in basic installation of instrumentation. The field is now treated as a side job that anybody can do. Pity we have to repeat the mistakes of our fathers. What you have now in the field of instrumentation is a bunch of young punks that don't understand controls unless it has a microprocessor in it. Even if it has all the"Buck Rogers"stuff in it, it must be installed and serviced correctly! I understand the power of computer based systems because I converted many single loop systems to one. The computer is a powerful part of a modern control system, but it is still a part.

Furthermore, I spent the late 1990s replacing the computer systems we put in the 1980s, so that equipment gets just as outdated, if not quicker than the systems Lipták describes.

Mark Deshaies, Calpine Corp.

Response:

You are absolutely right. The computer is nothing more than a tool, and in that sense, it knows nothing more than say a screwdriver or a chisel. A statue is not created by the chisel, but by the artist. Similarly, in process control, the knowledge comes from the user who understands the controlled process. Neither the programmer in the vendor's offices nor the fast talking DCS salesman can substitute for that knowledge.Yet if they leave it out, the control system will not work because a process can only be controlled if it is understood.

Béla G. Lipták P.E., Stamford, CT

Worth the effort

In May 2005 InTech, Andrey Romanenko's letter to the editor cautioned automation engineers about potential pitfalls or patent infringement using XML technology, in response to "Under the Hood of XSLT" (February 2005). Romanenko's comments were directed primarily towards the OPC XMLDA specification from the OPC Foundation, however, not the subject matter of the article.

It is difficult for automation engineers to keep up with the rapid changes in technology. Visual Basic for Applications is found in many HMI applications, but in some cases, it is a relatively recent addition. Four years ago, Microsoft introduced VB.Net while the old VB is headed toward obsolescence. For automation engineers that have not yet learned the VB languages, the question arises, should one learn the old VB or the new?

The article was meant to point to XML/XSLT as important technology that is not simply a fad and one that can help automation engineers to execute projects much more efficiently. If a system can import/export code as XML, engineers have an opportunity to manage changes, modifications, replication, and many other common automation project tasks in 50 to 90% less time than ever before. Throw caution to the wind, and learn this technology. Whether using OPC XMLDA or not, XML and XSLT are easy to learn and well worth the effort.