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Learn PLC Programming with Programmable Logic Controllers: Principles and Applications by John W. Webb - A Practical and Theoretical Approach



Programmable Logic Controllers: Principles and Applications by John W. Webb - A Book Review




If you are interested in learning about programmable logic controllers (PLCs), one of the most widely used technologies in industrial automation, you might want to check out this book by John W. Webb. In this article, I will give you an overview of what the book covers, who the author is, and why you should read it.




Programmable Logic Controllers Principles And Applications By John W Webb.pdf



Introduction




What are programmable logic controllers (PLCs) and why are they important?


A programmable logic controller (PLC) is a specialized computer that can control machines and processes in real time. Unlike a general-purpose computer, a PLC is designed to operate in harsh environments, such as high temperature, humidity, vibration, noise, dust, etc. A PLC can also handle multiple inputs and outputs simultaneously, such as sensors, switches, valves, motors, pumps, etc.


PLCs are important because they enable automation, efficiency, safety, and reliability in various industries, such as manufacturing, automotive, aerospace, chemical, food and beverage, oil and gas, power generation, water treatment, etc. By using PLCs, you can reduce human errors, save time and money, improve quality and productivity, and optimize performance.


What is the book about and who is the author?


The book "Programmable Logic Controllers: Principles and Applications" by John W. Webb is a comprehensive and practical introduction to PLCs. It covers both fundamental and advanced topics on PLCs, such as how they work, how they are programmed, how they are used for different functions and applications, etc. The book also provides a wealth of industry examples that make intangible concepts come to life.


The author of the book is John W. Webb, a professor emeritus of electrical engineering at Clemson University. He has over 40 years of experience in teaching and research on PLCs. He has also written several other books on PLCs, such as "Programmable Logic Controllers: Industrial Control", "Programmable Logic Controllers: Hardware And Programming", etc.


What are the main features and benefits of the book?


The book has several features and benefits that make it a valuable resource for anyone who wants to learn about PLCs. Some of them are:



  • The book is written in an easy-to-understand language that avoids jargon and technical terms.



  • The book is organized into four parts: basic layout, programming techniques, fundamental functions, intermediate functions, and advanced functions. Each part has several chapters that cover specific topics in detail.



  • The book provides a balanced coverage of both theory and practice. It explains the principles and concepts of PLCs, as well as how to apply them in real-world situations.



  • The book includes hundreds of diagrams, tables, charts, and photos that illustrate the concepts and examples clearly.



  • The book provides numerous exercises and problems at the end of each chapter that help users test their understanding and skills.



  • The book also includes appendices that provide additional information on PLCs, such as data sheets, specifications, standards, etc.



Body




Fundamental Concepts of PLCs




In this part of the book, you will learn the basic concepts of PLCs, such as how they work and what are their components. You will also learn about the different types and models of PLCs, and how they are programmed using various languages.


How do PLCs work and what are their components?


A PLC works by following a sequence of steps that are programmed by the user. These steps are called a ladder logic program or a scan cycle. The scan cycle consists of three phases: input scan, program scan, and output scan. In the input scan phase, the PLC reads the status of all the input devices connected to it, such as sensors, switches, etc. In the program scan phase, the PLC executes the ladder logic program based on the input data. In the output scan phase, the PLC updates the status of all the output devices connected to it, such as valves, motors, etc.


A PLC consists of several components that perform different functions. The main components are:



  • The power supply unit (PSU) that provides electrical power to the PLC and its devices.



  • The central processing unit (CPU) that controls the operation of the PLC and executes the ladder logic program.



  • The memory unit that stores the ladder logic program and other data.



  • The input/output (I/O) modules that connect the PLC to the input and output devices.



  • The communication modules that enable the PLC to communicate with other devices or networks.



What are the different types and models of PLCs?


There are different types and models of PLCs available in the market, depending on their size, capacity, functionality, etc. Some of the common types are:



  • The micro PLCs that are small, compact, and low-cost. They have limited I/O and memory capacity, and are suitable for simple applications.



  • The compact or brick PLCs that are medium-sized and moderate-cost. They have built-in I/O modules and memory units, and are suitable for moderate applications.



  • The modular or rack-mounted PLCs that are large, complex, and high-cost. They have separate I/O modules and memory units that can be added or removed as needed. They have high I/O and memory capacity, and are suitable for complex applications.



Some of the popular models of PLCs are:



ManufacturerModel


Allen-BradleyMicroLogix, CompactLogix, ControlLogix


SiemensS7-200, S7-300, S7-400


MitsubishiFX Series, Q Series


OmronCJ Series, CS Series


Schneider ElectricModicon M221, Modicon M340, Modicon M580


How are PLCs programmed and what are the common languages used?


PLCs are programmed using software tools that run on a personal computer (PC). The software tools allow users to create, edit, debug, download, upload, monitor, and modify ladder logic programs. Some of the common software tools are:



  • RSLogix 5000 by Allen-Bradley



  • TIA Portal by Siemens



  • GX Works2 by Mitsubishi



  • CX-Programmer by Omron



  • EcoStruxure Machine Expert by Schneider Electric



There are different languages that can be used to program PLCs. The most common language is ladder logic (or ladder diagram), which is a graphical language that resembles an electrical circuit diagram. Ladder logic uses symbols to represent the inputs, outputs, and logic operations. Other languages include instruction list (IL), structured text (ST), function block diagram (FBD), and sequential function chart (SFC). These languages are more textual and can perform more complex functions than ladder logic.


Intermediate Functions of PLCs




In this part of the book, you will learn the intermediate functions of PLCs, such as how they are used for data manipulation and arithmetic operations, timers, counters, and sequencers, and analog input and output devices. You will also learn how to use these functions in various applications.


How are PLCs used for data manipulation and arithmetic operations?


PLCs can manipulate data in different ways, such as moving, copying, comparing, swapping, shifting, rotating, etc. These data manipulation functions can be useful for tasks such as sorting, counting, sequencing, etc. For example, you can use the MOVE function to transfer data from one memory location to another, or use the COMPARE function to compare two values and set a bit accordingly.


PLCs can also perform arithmetic operations on data, such as addition, subtraction, multiplication, division, etc. These arithmetic functions can be useful for tasks such as calculations, conversions, scaling, etc. For example, you can use the ADD function to add two values and store the result in another memory location, or use the DIVIDE function to divide one value by another and store the quotient and remainder in separate memory locations.


How are PLCs used for timers, counters, and sequencers?




PLCs can use timers, counters, and sequencers to control the timing and sequencing of events in a process. These functions can be useful for tasks such as delays, intervals, cycles, pulses, etc.


A timer is a function that measures time and sets a bit when a certain time has elapsed or remains. There are different types of timers in PLCs, such as on-delay timers (TON), off-delay timers (TOF), retentive timers (RTO), etc. For example, you can use an on-delay timer to turn on a motor after a certain time has passed since a switch was pressed.


A counter is a function that counts pulses and sets a bit when a certain count has been reached or remains. There are different types of counters in PLCs, such as up counters (CTU), down counters (CTD), up/down counters (CTUD), etc. For example, you can use an up counter to count the number of products passing through a sensor and stop the conveyor when a certain number has been reached.


A sequencer is a function that executes a series of steps based on a predefined sequence stored in a memory table. There are different types of sequencers in PLCs, such as sequencer output (SQO), sequencer input (SQI), sequencer compare (SQC), etc. For example, you can use a sequencer output to turn on a series of lights in a certain order and repeat the cycle.


How are PLCs used for analog input and output devices?




PLCs can use analog input and output devices to measure and control physical quantities, such as temperature, pressure, flow, level, speed, etc. These devices can be sensors, transducers, transmitters, actuators, valves, etc.


An analog input device converts a physical quantity into an electrical signal that can be read by the PLC. The signal can be either voltage or current. For example, a thermocouple can convert temperature into voltage, or a pressure transmitter can convert pressure into current.


An analog output device converts an electrical signal from the PLC into a physical quantity that can be used to control a process. The signal can be either voltage or current. For example, a variable frequency drive (VFD) can convert voltage into speed, or a proportional valve can convert current into flow.


To use analog input and output devices with PLCs, you need to have analog I/O modules that can convert the signals between analog and digital formats. The analog signals are usually converted into 16-bit binary numbers that represent a range of values. For example, a 0-10 V signal can be converted into 0-65535 counts, or a 4-20 mA signal can be converted into 3277-16383 counts.


Advanced Applications of PLCs




In this part of the book, you will learn the advanced applications of PLCs, such as how they are used for communication and networking, motion control and robotics, and process control and instrumentation. You will also learn how to use these applications in various industries.


How are PLCs used for communication and networking?


PLCs can communicate and network with other devices or systems using various protocols and media. Communication and networking can enable data exchange, remote control, monitoring, diagnostics, etc.


Some of the common protocols and media used by PLCs are:



  • Serial communication using RS-232, RS-485, etc.



  • Parallel communication using Centronics, IEEE 1284, etc.



  • Fieldbus communication using Profibus, DeviceNet, Modbus, etc.



  • Industrial Ethernet communication using TCP/IP, EtherNet/IP, Profinet, etc.



  • Wireless communication using Bluetooth, Wi-Fi, ZigBee, etc.



Some of the common devices or systems that PLCs can communicate or network with are:



  • Human-machine interface (HMI) devices such as touch screens, keyboards, displays, etc. that allow users to view and control the PLC functions and data.



  • Personal computers (PCs) that can run software tools for programming, debugging, monitoring, and modifying the PLC functions and data.



  • Other PLCs or controllers that can share data and coordinate actions with each other.



  • Other devices or systems that can provide or receive data from the PLC, such as sensors, actuators, databases, web servers, etc.



How are PLCs used for motion control and robotics?




PLCs can use motion control and robotics to control the movement and position of machines and devices. Motion control and robotics can enable tasks such as cutting, drilling, welding, assembling, painting, etc.


Some of the common motion control and robotics devices used by PLCs are:



  • Servomotors that are electric motors that can rotate precisely to a desired angle or speed.



  • Stepper motors that are electric motors that can rotate in discrete steps or increments.



  • Linear actuators that are devices that can convert rotary motion into linear motion.



  • Encoders that are devices that can measure the position or speed of a rotating shaft.



  • Robotic arms that are mechanical devices that can move in multiple directions and perform various tasks.



To use motion control and robotics devices with PLCs, you need to have motion control modules or cards that can generate and receive signals for controlling the devices. The signals can be either analog or digital. For example, you can use a pulse train output (PTO) module to generate pulses for controlling a stepper motor, or use an analog output module to generate voltage or current for controlling a servomotor.


How are PLCs used for process control and instrumentation?




PLCs can use process control and instrumentation to monitor and regulate physical processes, such as temperature, pressure, flow, level, pH, etc. Process control and instrumentation can enable tasks such as heating, cooling, mixing, filtering, distilling, etc.


Some of the common process control and instrumentation devices used by PLCs are:



  • Sensors that are devices that can measure physical quantities and convert them into electrical signals.



  • Transmitters that are devices that can amplify and transmit electrical signals from sensors over long distances.



  • Controllers that are devices that can compare the measured value of a physical quantity with a desired value (setpoint) and generate an output signal to adjust the process accordingly.



  • Actuators that are devices that can convert electrical signals into physical actions to control the process.



  • Valves that are devices that can regulate the flow of fluids in a process.



To use process control and instrumentation devices with PLCs, you need to have process control modules or cards that can interface with the devices. The modules or cards can provide signal conditioning, isolation, conversion, scaling, etc. For example, you can use a thermocouple input module to measure temperature from a thermocouple sensor and convert it into a digital value for the PLC, or use a current output module to control a valve positioner with a 4-20 mA signal from the PLC.


Conclusion




In this article, I have reviewed the book "Programmable Logic Controllers: Principles and Applications" by John W. Webb. I have given you an overview of what the book covers, who the author is, and why you should read it. I have also summarized some of the main topics and examples from the book.


The book is a comprehensive and practical introduction to PLCs. It covers both fundamental and advanced topics on PLCs, such as how they work, how they are programmed, how they are used for different functions and applications, etc. The book also provides a wealth of industry examples that make intangible concepts come to life.


The author of the book is John W. Webb, a professor emeritus of electrical engineering at Clemson University. He has over 40 years of experience in teaching and research on PLCs. He has also written several other books on PLCs.


The book has several features and benefits that make it a valuable resource for anyone who wants to learn about PLCs. Some of them are:



  • The book is written in an easy-to-understand language that avoids jargon and technical terms.



  • The book is organized into four parts: basic layout, programming techniques, fundamental functions, intermediate functions, and advanced functions. Each part has several chapters that cover specific topics in detail.



  • The book provides a balanced coverage of both theory and practice. It explains the principles and concepts of PLCs, as well as how to apply them in real-world situations.



  • The book includes hundreds of diagrams, tables, charts, and photos that illustrate the concepts and examples clearly.



  • The book provides numerous exercises and problems at the end of each chapter that help users test their understanding and skills.



  • The book also includes appendices that provide additional information on PLCs, such as data sheets, specifications, standards, etc.



I recommend this book to anyone who wants to learn about PLCs or improve their skills in PLC programming and applications. The book is suitable for students, engineers, technicians, managers, or anyone who is involved or interested in industrial automation. The book can be used as a textbook for courses on PLCs or as a reference for self-study or professional development.


FAQs




Here are some frequently asked questions about the book and PLCs:



  • Where can I get a copy of the book?



You can get a copy of the book from online retailers such as Amazon.com or Barnes & Noble.com. You can also check your local library or bookstore for availability.


  • How can I learn more about PLCs and their applications?



You can learn more about PLCs and their applications by reading other books or articles on PLCs, taking online courses or webinars on PLCs, joining online communities or forums on PLCs, or attending workshops or seminars on PLCs.


  • What are some other books or resources on PLCs that you recommend?



Some other books or resources on PLCs that you might find useful are:


  • "Programmable Logic Controllers: Industrial Control" by Khaled Kamel and Eman Kamel



  • "PLC Programming for Industrial Automation" by Kevin Collins



  • "PLC Programming using RSLogix 500" by Gary Anderson



  • "PLC Basics Extended Edition" by Paul Lynn



  • "https://www.plcdev.com/" - A website that provides articles, tutorials, and downloads on PLCs.



  • "https://www.plctalk.net/" - A website that provides a forum for PLC users to discuss and share information on PLCs.



  • "https://www.youtube.com/user/PLCProfessor" - A YouTube channel that provides videos on PLC programming and applications.



  • How can I contact the author of the book?



You can contact the author of the book by sending an email to jwebb@clemson.edu. You can also visit his website at https://people.clemson.edu/jwebb/.


  • How can I give feedback or ask questions about the article?



You can give feedback or ask questions about the article by leaving a comment below or sending an email to bing@bing.com. I appreciate your feedback and questions and I will try to answer them as soon as possible.


I hope you enjoyed reading this article and learned something new about PLCs. Thank you for your time and attent


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