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

Understanding structs

Structs are special data structures that allow you to group logically related data into a single data structure. Structs in IEC 61131-3 work very similarly to a struct in a C-like language. They are custom data types that contain variables of different data types in a singular data structure. If you’ve never programmed in a C-like language, structs may seem a lot like classes, a concept that will be covered later.

Declaring a struct

Creating a struct is very similar to creating a GVL. Similar to a GVL, you create a struct with the following steps:

  1. Right-click Application.
  2. Hover over Add Object.
  3. Click DUT.

When you finish these steps, you should see a wizard that is very similar to the wizard used to create a GVL, except that it has a few more options. The wizard can be viewed in Figure 4.12. For now, the only thing that you will need to do is change DUT in the Name field to motorStruct and click Add. Once you click Add, a new...