It is possible to convey electrical power and communicate analog information over the same two wires using 4…
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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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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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I remember first learning about the world-wide Internet, and wondering what it actually looked like. The first…
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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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Learning PLC programming is a very important skill. If your job involves programming, then you will likely…
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DC electric current signals may also be used to communicate process measurement information from transmitters…
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There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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pH is the measurement of the hydrogen ion activity in a liquid solution. It is one of the most common forms of…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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Layer 1 of the OSI Reference Model is where we define the “physical” elements of a digital data…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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Some of the simplest types of digital communication networks found in industry are defined by the EIA…
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Labwork is an essential part of any science-based curriculum. Here, much improvement may be made over the…
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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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The efficient identification and correction of instrument calibration errors is an important function for…
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A unique form of technical diagram for describing the abstract functions comprising a control system (e.g. PID…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…
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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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A form of protection against faults on long-distance power lines is called distance relaying, so named because…
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A fundamental limitation of proportional control has to do with its response to changes in setpoint and…
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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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Learning is not merely a process of information transfer. It is first and foremost a transformation of…
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As we have seen, feedforward control is a way to improve the stability of a feedback control system in the…
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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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There are multiple motives for compromising the security of an industrial control system, some of which…
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Weight-based level instruments sense process level in a vessel by directly measuring the weight of the vessel.…
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All masses require force to accelerate (we can also think of this in terms of the mass generating a reaction…
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Perhaps the most confusing aspect of discrete sensors is the definition of a sensor’s normal status.…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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Some problem-solving techniques are unique to quantitative problems, involving mathematical calculations. In…
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Valves can experience a number of problems, most of them either preventable or repairable. These problems can…
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Level gauges are perhaps the simplest indicating instrument for liquid level in a vessel. They are often found…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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DC electric current signals may also be used to communicate process measurement information from transmitters…
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A very common method for directly controlling low flow rates of fluids is to use a device known as a metering…
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Hydrogen ion activity in aqueous (water-solvent) solutions is a very important parameter for a wide variety of…
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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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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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Visualizing the actions of P, I, and D tuning parameters using graphs is extremely useful in predicting the…
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A fluid is any substance having the ability to flow: to freely change shape and move under the influence of a…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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Fluid pressure exerts force on any surface area it contacts, as described by the formula \(F = PA\). One…
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The concepts of calibration (trimming) and ranging are often difficult for new students of instrumentation to…
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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
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A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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Perhaps the simplest form of solid or liquid level measurement is with a float: a device that rides on the…
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pH is the measurement of the hydrogen ion activity in a liquid solution. It is one of the most common forms of…
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These fortifications focus on human behavior rather than system design or component selection. In some ways…
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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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