Given that the primary 5th edition was published over two decades ago, it is no longer on the shelves of most bookstores. However, it is still widely available through various channels. It can be found on like eBay, Amazon, and AbeBooks. Many university and public libraries still carry it in their collections. The PDF version of the 5th edition is also available from commercial eTextbook vendors as a legitimate purchase. Furthermore, the international edition published by PHI Learning is often more affordable and widely available, particularly in India and other regions.
Move (MOV), Math (ADD, SUB), and Comparison instructions. C. Industrial Applications
This article provides a comprehensive overview of the principles, core architectures, programming methodologies, and industrial applications covered in this seminal text, serving as a valuable reference guide for students and professionals looking to master PLC systems. 1. Introduction to Programmable Logic Controllers (PLCs) Given that the primary 5th edition was published
Beyond basic on/off switching, Webb introduces critical functional blocks:
Stores both the operating system (firmware) and the user-generated control program. Many university and public libraries still carry it
This section bridges the gap between basic and advanced topics, covering arithmetic functions, number comparison, and numbering systems used for PLC number conversion functions.
The PLC performs internal diagnostics and manages communication with programming terminals, Human-Machine Interfaces (HMIs), or other networked PLCs before restarting the cycle. Move (MOV), Math (ADD, SUB), and Comparison instructions
: On-Delay (TON) and Off-Delay (TOF) blocks used to control the duration of events.
A critical concept detailed in Webb's book is the sequential operation known as the . Understanding this process is vital for writing predictable and bug-free logic.
: The processor writes the updated output states from the memory file to the physical output channels (e.g., motors, valves, indicator lights).
Overall, I highly recommend "Programmable Logic Controllers: Principles and Applications" by John W. Webb to anyone interested in learning about PLCs and their applications in industrial automation. The book provides a comprehensive and practical introduction to PLCs, making it an excellent resource for students, practicing engineers, and professionals.