60th Anniversary: CE History from 60, 30, and 15 years ago on process analysis, data buses, and process analyzer trends
Happy 60th, Control Engineering! Help us celebrate by looking at issues from 60, 30, and 15 years ago. Control Engineering magazine first published in September 1954. This monthly column in 2014 will review coverage in issues 60, 30, and 15 years ago. While technologies have progressed since then, topics below (process analysis, data buses, and process analyzer trends) remain relevant today.
October 1954: Control in Evolution: Analysis moves from lab to line
Lay prophets of the factory without workers pridefully point to today's highly instrumentized chemical processing plant. Huge quantities of materials flow through its complex network of pipes into fractionation columns, purification towers, and reactors with very little human attention. Enormous amounts of finished product are pumped into pipeline and storage tanks without ever having been seen by human eyes.
That such a complicated system will function at all is due largely to the many dependable control instruments present in any processing plant. They control the flow of raw material and product through the maze of pipes. They provide exactly the proper pressure and temperature to produce the highest product yield. In short, these instruments make this the closest approach yet to a completely automatic factory.
October 1984: Data buses expand control horizons
The English language permits one word or phrase to have many different meanings. A word's meaning changes because of the way it is used, modified, or placed in a sentence, to name a few examples. The term "data bus" commonly refers to a mechanical and electrical connection where digital information is transmitted from one device to another. This definition is simple, but its interpretation takes many forms.
One form of data bus comes from board-level computers. STD, Multi-, VME-, Q-, STE-, VERSA-, and CIM- all use "bus" in their names. Digital data is passed from one board to another on a parallel channel, multiple byte-wide backplane at megahertz speeds. The distance covered, though, is measured in inches, as these data transfers occur in spaces usually no longer than a 19-in. rack.
An operational philosophy that may be learned from such sophisticated bus structures is the use of multiple special function paths to make communication more efficient. Several of the bus structures feature physically different and separate parallel and serial data buses to make the board level computer systems more effective. The same is applicable to control systems in general.
October 1999: Trends in process analyzers
Since the beginning of time, humans have used the most fundamental of all analyzers-their nose-to sniff the quality of air, food, or drink. Over the ages, great advances have refined the methods by which we analyze a given substance or product to determine its composition. Today, users have a wide variety of choices to analyze gases, liquids, and solids. Each technology has advantages and disadvantages that must be weighed against the application for successful implementation.
Virtually all process analytical systems today originate from the laboratory environment. Users were often the first to try and reconfigure these laboratory instruments for direct on-line measurements. In situations where a laboratory instrument was incompatible with a process, users developed their own instrumentation to perform on-line analysis. In time, suppliers began to offer dedicated process analyzers based on their own designs or used-licensed technologies. Often, these early systems did not demonstrate robust design principles, were complex, and required frequent maintenance and oversight by highly trained technical personnel. This led to a poor reputation, often justified, for many process analytical techniques.
- 2014 edits, to fit this page, by Chris Vavra, production editor, CFE Media, email@example.com.
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