An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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A bridge circuit is basically a pair of voltage dividers where the circuit output is taken as the difference…
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An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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Imagine a major marathon race, where hundreds of runners gather in one place to compete. When the starting gun…
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Light has long been used as a long-range signaling medium. While communication by light through open air is…
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These fortifications focus on human behavior rather than system design or component selection. In some ways…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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There are multiple motives for compromising the security of an industrial control system, some of which…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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One of the great benefits of digital technology is the ability to communicate vast amounts of information over…
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An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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In the United States, the ANSI and IEEE organizations have standardized a set of numerical codes referring to…
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At the next OSI Reference Model layer (layer 4) is a set of protocols specifying how reliable communication…
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Cyber-security seems to have its own vocabulary, ranging from unwieldy technical acronyms to slang terms…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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I remember first learning about the world-wide Internet, and wondering what it actually looked like. The first…
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Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float directly sets…
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Cyber-security seems to have its own vocabulary, ranging from unwieldy technical acronyms to slang terms…
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A hand switch is exactly what the name implies: an electrical switch actuated by a person’s hand motion.…
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The simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
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Solids tend to expand when heated. The amount that a solid sample will expand with increased temperature…
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Learning from reading printed text is a kind of problem-solving activity it is own right. The problem is how…
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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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Atom: the smallest unit of matter that may be isolated by chemical means. Particle: a part of an atom,…
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Up until this point, we have explored various types of instrumentation diagram, each one making reference to…
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A variety of technologies exist to measure the quantity of stored material in a vessel. For liquid…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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Few areas of mathematics are as powerfully useful in describing and analyzing the physical world as calculus:…
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Most of these formulae appear in molecular chemical form rather than structural form. For example, ethanol…
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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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The following animation shows a rotating phasor in three-dimensional form. The phasor rotates in a complex…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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