LETTERS

Though I highly respect BeIa Liptak, Richard Udden is right on with his May 2004 InTech letter, "Defining DCS." While ISA can rebirth itself as "Instrumentation, Systems and Automation" with no objection, neither Bela nor even ISA has the historical much less moral authority to redefine the acronym "DCS"away from its original creation as "distributed control system."

Regardless, word of this redefinition does not appear to have been sufficiently communicated to the rest of the controls industry to make a difference.

Using Control Engineering's online Technical Encyclopedia of over 20,000 technical terms, there are five different definitions listed for the acronym DCS, including of course distributed control system. But none of these definitions include "digital control system." And Honeywell, more than anyone else it could be argued, may have the historical authority to rewrite the genesis of the word DCS. Other control system vendors such as Foxboro have also implicitly recognized that authority when they tried to paint the DCS as a dinosaur over a decade ago. But this is academic, as I have not seen Honeywell putting forth any proposal to change the designation of DCS. I have seen them use the term "hybrid," as have others, to include both DCS and PLC. And the distinction between these systems and SCADA appears to be disappearing as well.

So while it may be seen as commendable by some to "update" the meaning of the commonly used acronym DCS for current times, for others such as myself, it is seen as an attempt to rewrite history and in so doing, destroy the legacy of these various systems in the control systems arena.

Having worked with centralized control systems from IBM and Foxboro before they were replaced with distributed control systems, the distinction between the two is a lesson in history that should not be forgotten.

Ted Porter, Enterprise Products Operating LP, Houston, Texas

Intrinsically safe Ethernet

I write in response to the article ["C-fieldbus is a gas," Networking & Communications department, November 2003 InTech] and the claim that "Ethernet does not readily become intrinsically safe without changing it in such a way that it is no longer Ethernet." I would argue with this view in that we are currently using an intrinsically safe 10/100 megabits per second industrial Ethernet system. This system has been approved and certified by, arguably, one of the most stringent and respected testing houses in the world: the British SIRA testing house. It is ATEX ia approved for Group I gases. We are also further developing the system technically to increase its functionality.

John Ford, UK Coal Mining Ltd., South Yorkshire, England

InTech News: Trim fat from wasting hydrocarbons, study says

InTech's online newsletter, InTech News, offered this report on 27 May: More judicious use of hydrocarbon-based fossil fuels would reduce U.S. energy consumption by 33% and save consumers $438 billion a year by 2014, according to an analysis by Cornell University ecologists.

David Pimentel, Cornell professor of ecology, and 11 student ecologists found the most fat for trimming-with the best potential for major energy savings-in the transportation, residential heating and cooling, industrial, and food-production sectors.

Energy conservation and implementation of energy-efficient technologies also would allow significant savings in the production and use of chemicals, paper and lumber, household appliances, lighting and metals, the analysis showed.

American taxpayers could save an estimated $39 billion a year by insisting that the government end subsidies to the energy industries, according to Pimentel. "The next time you're pumping gas or paying the heating bill, ponder this: As high as fuel prices are in this country, they would be even higher without government subsidies to prop up the industry," he said. "Instead of paying at the pump, every American family is paying about $410 in taxes each year for subsidies that keep gasoline prices and other energy product prices artificially low. This policy encourages greater consumption and importation of more oil and natural gas. Ending subsidies and pricing energy at its true cost would stimulate the use of conservation and energy-efficient technologies, and result in net savings."

The analysis occurred during a yearlong, graduate-level class called Environmental Policy in which students, under Pimentel's direction, investigated complex environmental issues by compiling previously published studies and drawing conclusions.

Response

This is a response to the ["Trim fat from wasting hydrocarbons, study says"] article from the In Tech News online magazine.

The article quotes that the average American pays $410 a year in subsidies to keep fuel prices artificially low. I say it is a pretty good deal. A few back-of-the-napkin calculations will show that at today's prices $410 gets you about 200 gallons in gas. For a conservative 20 mpg, that equates to only about 4,000 miles.