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

HMI implementation

The first thing we need to do is start declaring variables. For this example, we are going to put all the variables that control the HMI in a global variable list (GVL) called vars for ease of use. For this project, we are going to declare the variables in groups such as LEDs and so on to make it easier for you, the reader, to follow along with the code. The first set of variables we are going to work on are the LED variables.

LED variables

We have three LEDs that are used as temperature indicators and one LED that is used as a power indicator. We are going to create four Boolean variables, as follows:

 PROGRAM PLC_PRG
VAR
     //LEDs
     power       : BOOL;
     safe_temp   : BOOL;
     target_temp : BOOL;
END_VAR

The following will show you which variables to map to which LEDs:

  • The power variable...