Book Image

Mastering PLC Programming

By : Mason White
Book Image

Mastering PLC Programming

By: Mason White

Overview of this book

Object-oriented programming (OOP) is a new feature of PLC programming that has taken the automation world by storm. This book provides you with the necessary skills to succeed in the modern automation programming environment. The book is designed in a way to take you through advanced topics such as OOP design, SOLID programming, the software development lifecycle (SDLC), library design, HMI development, general software engineering practices, and more. To hone your programming skills, each chapter has a simulated real-world project that’ll enable you to apply the skills you’ve learned. In all, this book not only covers complex PLC programming topics, but it also removes the financial barrier that comes with most books as all examples utilize free software. This means that to follow along, you DO NOT need to purchase any PLC hardware or software. By the end of this PLC book, you will have what it takes to create long-lasting codebases for any modern automation project.
Table of Contents (25 chapters)
1
Part 1 – An Introduction to Advanced PLC Programming
6
Part 2 – Modularity and Objects
10
Part 3 – Software Engineering for PLCs
14
Part 4 – HMIs and Alarms
19
Part 5 – Final Project and Thoughts

Getting to know methods

The term method has been thrown around a few times thus far in the book. A method is a special type of function that belongs to a function block. Methods are members of function blocks that consist of blocks of code that are executed when called. Without methods, a function block is mostly useless. To conceptualize a method, consider the blueprint example before. If the function block is a car, then the methods are the brakes and engine of said car.

Unlike the functions we explored in Chapter 5, methods are not global. This means that they cannot be called from anywhere like the functions we previously explored. Essentially, the only place that can call these functions is a file with an object to the function block or from somewhere inside the function block, such as another method.

To create a method, you must first have a function block. Since we already have a Calculator function block, we are going to add four methods to it that will handle addition...