Webb’s book is the teach a person to fish of PLCs. It won’t get you a job programming a CompactLogix tomorrow, but it will stop you from being lost when someone says “scan cycle,” “retentive timer,” or “seal-in circuit.”
First published in the early days of programmable logic controllers, this book did something revolutionary: it translated complex electrical engineering concepts into language that electricians and maintenance personnel could understand.
" Programmable Logic Controllers: Principles and Applications " by John W. Webb is a foundational text detailing the hardware, programming, and industrial applications of PLCs. The text covers the modular design of CPUs, I/O modules, and the critical five-step scan cycle—input scan, program execution, output scan, housekeeping, and loop—essential for industrial automation. Learn more about the basics of PLC operations at Unitronics . Share public link Webb’s book is the teach a person to fish of PLCs
Webb provides thorough examples of ladder logic programming, focusing on:
Before searching for a free PDF, check Google Books , Internet Archive (Textbooks) , or your university’s O'Reilly Safari subscription. Many libraries offer legal digital lending. Webb is a foundational text detailing the hardware,
At its core, the book provides a that demystifies the complex subject of industrial control systems. It is widely used for undergraduate-level courses in PLCs, electronic controls, and industrial electronics maintenance training programs. The book's primary strength is its ability to guide a beginner from a complete novice to someone with a working understanding of PLC principles, all while being firmly grounded in real-world applications.
The textbook is designed for classroom and self-study use. Key features include: Share public link Webb provides thorough examples of
– The book traces the evolution of PLCs from relay‑based systems to networked, microprocessor‑driven controllers. Understanding that progression helps engineers appreciate why modern PLCs work the way they do.
, grew alongside the technology. He spent nights mapping out Ladder Logic
Connect the PLC to sensors, switches, motors, and solenoids. 3. Relay Logic and PLC Programming