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

Testing the application

Now that we have the code implemented, we can run a few test cases to see if the code works as expected. If you look at the code, we have an oven_temp variable that in real life would be tied to some type of thermal sensor. For our purposes, we are going to control it manually to simulate the conditions inside the oven. In real-world automation programming, this is a common technique. We don’t always want to heat the oven to the target temperature until we know for sure the software is working; simply writing values to that variable will suffice. With all that being said, we can now start testing the application by testing out the door.

Testing the door lock

We are going to start with the most basic and safety-critical part: testing the door. Essentially, we want to ensure the door is locking and unlocking properly. For this, we are going to use the following test case:

Figure 15.15 – Test case

Figure 15.15 – Test case

The test case...