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

Examining interfaces

If you read a textbook on a traditional language such as Java or C#, you will see that interfaces are often referred to as contracts. When you opt to use an interface, you are telling CODESYS that you agree to, at the very least, implement all the methods prototyped in the interface. However, in my opinion, this is a little confusing.

Generally, when I describe an interface to a new programmer, I usually describe them as a model for something. For example, if we are building an airplane, we will need certain things such as wings, an engine, and a cockpit regardless of whether we are building a prop plane or an F-35 jet fighter. Obviously, for each type of plane, these parts are going to be different. As such, when we implement an interface, we are telling our function block that we are going to use the methods that are declared in the interface but those methods may have different implementations.

To demonstrate how an interface works, let’s implement...