An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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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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I remember first learning about the world-wide Internet, and wondering what it actually looked like. The first…
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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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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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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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There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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DC electric current signals may also be used to communicate process measurement information from transmitters…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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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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One of the great benefits of digital technology is the ability to communicate vast amounts of information over…
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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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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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It is possible to convey electrical power and communicate analog information over the same two wires using 4…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…
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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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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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Steam boilers are very common in industry, principally because steam power is so useful. Common uses for steam…
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In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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Perhaps the most important rule to obey when using pneumatic instruments is to maintain clean and dry…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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A different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…
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To review, voltage is the measure of potential energy available to electric charges. Current is the uniform…
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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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A vertical column of fluid generates a pressure at the bottom of the column owing to the action of gravity on…
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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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Filled-bulb systems exploit the principle of fluid expansion to measure temperature. If a fluid is enclosed in…
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A pressure switch is one detecting the presence of fluid pressure. Pressure switches often use diaphragms or…
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As previously defined, calibration refers to the checking and adjustment of an instrument so that its output…
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Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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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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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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A much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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A positive displacement flowmeter is a cyclic mechanism built to pass a fixed volume of fluid through with…
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Mechanical pressure-sensing elements include the bellows, the diaphragm, and the bourdon tube. Each of these…
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A damper (otherwise known as a louvre) is a multi-element flow control device generally used to throttle large…
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Shown here is a partial listing of principles applied in the subject matter of this chapter, given for the…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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The most popular form of signal transmission used in modern industrial instrumentation systems (as of this…
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What is Calibration? To calibrate an instrument means to check and adjust (if necessary) its response so the…
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Feedback obtained from industrial users of FF reveal a common pattern: Fieldbus is a powerful and reliable…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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As a general rule, high achievement only takes place in an atmosphere of high expectations. Sometimes these…
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Flow, by definition, is the passage of material from one location to another over time. So far this chapter…
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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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A hand switch is exactly what the name implies: an electrical switch actuated by a person’s hand motion.…
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A great many precision instruments use the principle of balance to measure some quantity. Perhaps the simplest…
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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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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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