One of the great benefits of digital technology is the ability to…
An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973,…
Cyber-security seems to have its own vocabulary, ranging from unwieldy…
I remember first learning about the world-wide Internet, and wondering…
The vast majority of PID controllers in service today are digital in…
In a manually-controlled process, a human operator directly actuates…
Many years ago, when I was first learning about electricity, I…
Programmable logic controllers are essentially nothing more than…
Every programmable logic controller must have some means of receiving…
At the next OSI Reference Model layer (layer 4) is a set of protocols…
These fortifications focus on human behavior rather than system design…
A completely different way of measuring liquid level in vessels is to…
There are multiple motives for compromising the security of an…
Developed by the Modicon company (the original manufacturer of the…
An exciting development in industrial instrumentation is the…
Imagine a major marathon race, where hundreds of runners gather in one…
A bridge circuit is basically a pair of voltage dividers where the…
A design-based fortification is one rooted in technical details of…
In the United States, the ANSI and IEEE organizations have…
Light has long been used as a long-range signaling medium. While…
Imagine a liquid-level control system for a vessel, where the position…
As we have seen, feedforward control is a way to improve the stability…
To calibrate an instrument means to check and adjust (if necessary)…
Although it seems each model of PLC has its own idiosyncratic standard…
The following photograph shows a large air blower in a wastewater…
RTDs are completely passive sensing elements, requiring the…
Control strategies such as cascade, ratio, feedforward, and those…
Area refers to the size of two-dimensional surface. Volume refers to…
A wise PLC programmer once told me that the first thing any aspiring…
An important design parameter of a control valve is the position it…
A pressure switch is one detecting the presence of fluid pressure.…
Measuring the flow rate of liquid through an open channel is not…
Fluid pressure exerts force on any surface area it contacts, as…
The advent of “smart” field instruments containing…
A technological advance introduced in the late 1980’s was HART,…
A pneumatic controller receives a process variable (PV) signal as a…
(Will be addressed in future versions of this book)
All substances are comprised of various elements in various…
Any conductor possesses a characteristic called inductance: the…
Most pneumatic instruments use a simple but highly sensitive mechanism…
Valve actuators provide force to move control valve trim. For precise…
A different strategy for controlling the flow of fluid is to insert a…
A whole class of problem-solving techniques focuses on altering the…
As we have seen, the concept of differentiation is finding the…
An important design parameter of a control valve is the position it…
The concepts of calibration (trimming) and ranging are often difficult…
The purpose of a control valve actuator is to provide the motive force…
A hand switch is exactly what the name implies: an electrical switch…
While 50 and 51 (instantaneous and time overcurrent) relay functions…
Classical mechanics (often called Newtonian mechanics in honor of…
Calculus has a reputation for being difficult to learn, and with good…
Any physical location in an industrial facility harboring the…
A simple control system drawn in block diagram form looks like this:…
It is possible to convey electrical power and communicate analog…
The two “process variables” we rely on most heavily in the…
A positive displacement flowmeter is a cyclic mechanism built to pass…
First, let us review some of the properties of differentials and…
An extremely important topic in engineering is that of transfer…
A fluid is any substance having the ability to flow: to freely change…
Since we often use electricity to convey energy from one location to…
