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Download Programmable Logic Controllers Principles and Applications by John W Webb PDF for Free and Master PLCs


Programmable Logic Controllers Principles and Applications by John W Webb PDF Free 16




If you are interested in learning more about programmable logic controllers (PLCs), you might want to check out this book by John W Webb. In this article, we will give you a brief introduction to what PLCs are, what are their principles and applications, and why you should read this book. We will also show you how to download the PDF version of the book for free.




Programmable Logic Controllers Principles And Applications By John W Webb Pdf Free 16



What are Programmable Logic Controllers (PLCs)?




PLCs are electronic devices that can control and automate various processes and machines. They are widely used in different industries, such as manufacturing, automation, robotics, and more. PLCs can receive input signals from sensors, switches, keyboards, etc., and produce output signals to actuators, motors, valves, displays, etc., based on a predefined logic program.


Definition and history of PLCs




The term "programmable logic controller" was coined by Richard E. Morley in 1968, who is considered the father of PLCs. He was working for Bedford Associates, a company that was contracted by General Motors to develop a replacement for the hard-wired relay systems that were used to control the hydraulic presses in their car factories. Morley and his team designed the first PLC, called Modicon 084, which was able to perform sequential logic operations using a stored program.


Since then, PLCs have evolved significantly in terms of size, speed, memory, functionality, and communication. Modern PLCs can handle complex tasks such as arithmetic operations, data manipulation, timers, counters, analog signals, network communication, etc.


Components and functions of PLCs




A typical PLC consists of four main components: power supply, central processing unit (CPU), input/output (I/O) modules, and programming device. The power supply provides the necessary voltage and current for the operation of the PLC. The CPU is the brain of the PLC that executes the logic program and coordinates the communication between the I/O modules and the programming device. The I/O modules connect the PLC to the external devices that provide input signals or receive output signals. The programming device is used to create, edit, download, or monitor the logic program that controls the PLC.


Advantages and disadvantages of PLCs




Some of the advantages of using PLCs are:


  • They are flexible and adaptable to different applications and requirements.



  • They are reliable and durable in harsh environments.



  • They are easy to program and troubleshoot using graphical or textual languages.



  • They can reduce wiring costs and space requirements compared to hard-wired systems.



  • They can improve productivity and quality by reducing human errors and increasing efficiency.



Some of the disadvantages of using PLCs are:


  • They can be expensive to purchase and maintain.



  • They can be vulnerable to electrical noise and interference.



  • They can be affected by power failures or software bugs.



  • They can have limited memory and processing capacity for complex applications.



  • They can require specialized training and skills to operate and program.



What are the principles and applications of PLCs?




PLCs operate based on a scan cycle that consists of three steps: input scan, program scan, and output scan. In the input scan, the PLC reads the status of all the input devices connected to it. In the program scan, the PLC executes the logic program stored in its memory. In the output scan, the PLC updates the status of all the output devices connected to it. This cycle repeats continuously until the PLC is turned off or stopped.


Basic principles of PLC programming




There are different languages that can be used to program a PLC, such as ladder logic, function block diagram, structured text, etc. Each language has its own syntax, rules, symbols, and advantages. However, they all share some common elements that define how a PLC program works. These elements are:


  • Contacts: These are symbols that represent input devices or internal conditions that can be either open or closed. They act like switches that allow or block current flow in a circuit.



  • Coils: These are symbols that represent output devices or internal actions that can be either energized or de-energized. They act like relays that turn on or off depending on current flow in a circuit.



  • Rungs: These are horizontal lines that connect contacts and coils in a logical sequence. They form a network that represents a part of a program.



  • Latches: These are circuits that use feedback loops to maintain an output state even after an input condition changes. They act like memory devices that store information in a program.



  • Timers: These are devices that measure time intervals or delays between events in a program. They can be either on-delay or off-delay timers.



  • Counters: These are devices that count pulses or events in a program. They can be either up-counters or down-counters.



Ladder logic




Ladder logic is one of the most popular languages for PLC programming. It is based on relay logic diagrams that were used to control hard-wired systems. It uses contacts and coils as basic symbols to create rungs that resemble a ladder. Ladder logic is easy to understand and implement for simple applications.


An example of a ladder logic program is shown below:


-----[ ]-----[ ]-----[ ]-----[ ]-----( )----- X1 X2 X3 X4 Y1 X1 = Start button X2 = Stop button X3 = Pressure switch X4 = Temperature switch Y1 = Motor


This program controls a motor (Y1) that starts when a start button (X1) is pressed and stops when a stop button (X2) is pressed or when either a pressure switch (X3) or a temperature switch (X4) is activated.


Function block diagram




Function block diagram is another language for PLC programming. It is based on graphical blocks that represent functions or operations that can be performed on input or output data. It uses lines to connect blocks in a logical flow. Function block diagram is suitable for complex applications that involve arithmetic calculations or data manipulation.


An example of a function block diagram program is shown below:


+------+ +------+ +------+ A +---+ B +---+ C +---+ +------+ +------+ +------+ v +------+ D +---+ +------+ v +------+ E +---+ +------+ v +------+ F +---+ +------+ v +------+ G +---+ A = Analog input B = Scaling block C = Offset block D = Addition block E = Multiplication block F = Subtraction block G = Analog output


This program performs some mathematical operations on an analog input (A) and outputs an analog signal (G). The scaling block (B) converts the input range into an engineering unit range. The offset block (C) adds or subtracts a constant value from the input signal. The addition block (D) adds two input signals together. The multiplication block (E) multiplies two input signals together. The subtraction block (F) subtracts one input signal from another.


Structured text




Structured text is another language for PLC programming. It is based on high-level text languages such as C or Pascal. It uses statements, expressions, variables, data types, operators, and control structures to create programs that can be executed by the PLC. Structured text is useful for advanced applications that require complex logic or calculations.


An example of a structured text program is shown below:


VAR x : INT; y : INT; z : INT; END_VAR x := 10; y := 20; z := x + y; IF z > 25 THEN DO_SOMETHING(); ELSE DO_SOMETHING_ELSE(); END_IF


This program declares three integer variables (x, y, and z) and assigns values to them. Then, it adds x and y and stores the result in z. Finally, it checks if z is greater than 25 and calls a function accordingly.


Common applications of PLCs in different industries




PLCs are widely used in various industries to control and automate different processes and machines. Some examples of PLC applications are:


Manufacturing




PLCs can control the production lines, assembly machines, conveyor belts, robots, etc., that are involved in manufacturing different products. For example, PLCs can control the speed, direction, and timing of the conveyor belts that move the raw materials and finished products. PLCs can also control the robots that perform tasks such as welding, painting, or packaging.


Automation




PLCs can control the automation systems that regulate the temperature, humidity, lighting, ventilation, security, etc., of a building or a facility. For example, PLCs can control the heating, ventilation, and air conditioning (HVAC) system that maintains a comfortable environment for the occupants. PLCs can also control the fire alarm system that detects and alerts in case of a fire.


Robotics




PLCs can control the robots that perform various functions such as exploration, entertainment, education, etc. For example, PLCs can control the robots that explore hazardous environments such as space or underwater. PLCs can also control the robots that interact with humans such as toys or pets.


Why should you read Programmable Logic Controllers Principles and Applications by John W Webb?




If you want to learn more about PLCs and how to program them using different languages and techniques, you might want to read this book by John W Webb. In this section, we will give you an overview and features of the book, as well as its benefits and drawbacks.


Overview and features of the book




Programmable Logic Controllers Principles and Applications by John W Webb is a comprehensive textbook that covers the theory and practice of PLCs. It was first published in 1988 and has been updated several times since then. The latest edition was published in 2016 and has 16 chapters.


The book covers topics such as:


  • The history and evolution of PLCs



  • The hardware and software components of PLCs



  • The programming languages and methods for PLCs



  • The design and troubleshooting of PLC systems



  • The applications and examples of PLCs in different industries



The book also features:


  • Clear explanations and illustrations of concepts and procedures



  • Numerous exercises and problems for practice and review



  • A CD-ROM that contains software tools and simulation programs for PLCs



  • A companion website that provides additional resources and updates



Benefits and drawbacks of the book




Some of the benefits of reading this book are:


  • You will gain a solid foundation and understanding of PLCs



  • You will learn how to program PLCs using different languages and techniques



  • You will be able to apply your knowledge to real-world scenarios and problems



  • You will enhance your skills and confidence in working with PLCs



Some of the drawbacks of reading this book are:


  • You might find some parts of the book too technical or detailed for your level or interest



  • You might need to supplement your reading with other sources or materials for more updated or specific information



  • You might need to invest time and effort to complete the exercises and problems in the book



  • You might need to purchase or access the software tools and simulation programs for PLCs



How to download the PDF for free?




If you are interested in reading this book but do not want to buy it or borrow it from a library, you might be wondering if you can download the PDF version for free. The answer is yes, but you need to be careful about where you get it from.


There are many websites that claim to offer free PDF downloads of books, but some of them might be illegal or unsafe. They might contain viruses or malware that can harm your computer or device. They might also violate the copyright laws or ethical principles that protect the authors' rights and interests.


Therefore, we recommend that you use only reputable and reliable sources to download free PDF books. One such source is PDF Drive (https://www.pdfdrive.com/), which is a search engine for PDF files. It allows you to search for millions of books on various topics and download them for free.


To download Programmable Logic Controllers Principles and Applications by John W Webb PDF for free from PDF Drive, you can follow these steps:


  • Go to https://www.pdfdrive.com/ on your browser.



  • Type "Programmable Logic Controllers Principles and Applications by John W Webb" in the search box and click on the magnifying glass icon.



  • Select the book from the list of results. You can check the details such as year, edition, pages, size, etc., before downloading.



  • Click on the green "Download" button on the right side of the page.



  • Wait for a few seconds until the download link appears.



  • Click on the link to save the PDF file on your computer or device.



  • Enjoy reading!



Conclusion




In this article, we have given you an introduction to what programmable logic controllers (PLCs) are, what are their principles and applications, and why you should read Programmable Logic Controllers Principles and Applications by John W Webb. We have also shown you how to download the PDF version of the book for free from a reliable source.


We hope that this article has been informative and helpful for you. If you want to learn more about PLCs and how to program them using different languages and techniques, we highly recommend that you read this book by John W Webb. It will provide you with a comprehensive and practical guide to PLCs that will enhance your knowledge and skills.


FAQs




Here are some frequently asked questions about PLCs and the book by John W Webb:



  • What are the advantages of using PLCs over hard-wired systems?



Some of the advantages of using PLCs over hard-wired systems are: flexibility, reliability, ease of programming, reduced wiring costs, improved productivity and quality.


  • What are the different types of PLCs?



There are different types of PLCs based on their size, capacity, functionality, and communication. Some examples are: micro PLCs, compact PLCs, modular PLCs, rack-mounted PLCs, distributed PLCs, etc.


  • What are the different standards for PLC programming languages?



The International Electrotechnical Commission (IEC) has defined a standard for PLC programming languages called IEC 61131-3. It specifies five languages: ladder logic (LD), function block diagram (FBD), structured text (ST), instruction list (IL), and sequential function chart (SFC).


  • What are some of the software tools and simulation programs for PLCs?



Some of the software tools and simulation programs for PLCs are: RSLogix 5000, CX-Programmer, STEP 7, CODESYS, LogixPro Simulator, PLCSIM, etc.


  • Where can I find more resources and updates about PLCs and the book by John W Webb?



You can find more resources and updates about PLCs and the book by John W Webb on the companion website: https://www.pearson.com/us/higher-education/program/Webb-Programmable-Logic-Controllers-Principles-and-Applications-6th-Edition/PGM334978.html



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