PLC Engineering: Programming in Practice: Ladder Logic, Function Block Diagram, Structured Text and Sequential Control

Industrial PLC software must do far more than switch outputs. A dependable program must coordinate operating modes, manage competing commands, supervise feedback, respond to faults, recover safely after interruptions, support diagnostics, and remain understandable long after commissioning.

PLC Engineering: Programming in Practice is a practical guide to building reliable, maintainable, and testable control software using Ladder Diagram, Function Block Diagram, Structured Text, and sequential programming. The manufacturer-neutral methods can be applied across different PLC platforms.

WHO THIS BOOK IS FOR

This book is written for:

• PLC programmers and automation engineers
• Industrial electricians and maintenance technicians
• Machine builders and commissioning specialists
• Control-system designers and software reviewers
• Engineering students and technical trainees

WHAT YOU WILL LEARN

Inside this book, you will learn how to:

• Translate machine requirements into structured PLC software
• Organize projects, tags, data types, and interfaces
• Build clear and dependable Ladder Logic circuits
• Apply timers, counters, comparisons, memory, and edge detection
• Use Function Block Diagram for signal processing and control
• Write Structured Text for calculations, loops, arrays, and data handling
• Create reusable functions, function blocks, and equipment objects
• Program motors, valves, sensors, actuators, and variable-frequency drives
• Separate commands, permissives, interlocks, trips, and feedback
• Manage Manual, Automatic, Local, Remote, and Maintenance modes
• Design alarms, diagnostic codes, and first-fault indication
• Develop sequences with explicit states and transition conditions
• Process analog signals and integrate PID control
• Exchange HMI commands, recipes, parameters, and production data
• Test software through simulation and controlled fault injection
• Diagnose live systems using online monitoring

TECHNICAL AREAS COVERED

The book examines the main programming methods, control structures, and diagnostic concepts used in industrial PLC applications, including:

• Ladder Diagram, Function Block Diagram, and Structured Text
• IEC 61131-3 programming concepts
• Timers, counters, latches, comparisons, and edge detection
• Functions, function blocks, and reusable equipment objects
• Motors, contactors, valves, cylinders, sensors, and drives
• Commands, permissives, interlocks, trips, and feedback supervision
• Manual, automatic, local, remote, and maintenance control
• Sequential control, state machines, and transition logic
• Analog scaling, filtering, validation, and PID control
• Alarm handling, diagnostic codes, and event management
• HMI communication, recipes, parameters, and production data
• Simulation, fault injection, online monitoring, and trace analysis
• Software reviews, standards, and lifecycle maintenance

WHY THIS BOOK MATTERS

Reliable PLC programming requires clear ownership. Automatic sequences, manual controls, remote systems, and maintenance functions may all request an action, but only one defined software object should control the final physical output.

The book also explains the differences between conditions, events, and states; commands and confirmed feedback; start permissives and run interlocks; temporary values and retained data. These distinctions help prevent repeated actions, unsafe restarts, hidden latches, missed transitions, sequence lockups, and outputs controlled from multiple locations.

Through practical examples and realistic industrial failure cases, the book shows how small software weaknesses become production faults—and how structured logic, reusable interfaces, diagnostics, and controlled testing prevent them.

Write clearer logic. Build reusable control structures. Diagnose faults faster.