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

Alarm acknowledgment

If you’ve noticed, thus far, when you throw an error alarm, the text doesn’t go away, whether it be an alarm in the banner or chart. This is because error alarms must be acknowledged. Essentially, if you throw an error, an alarm will be present, at least in text, if you do not acknowledge the alarm. An acknowledgment is basically a confirmation that an operator has seen the alarm and has decided to clear it. No matter whether you’re using a table or a banner, you will clear alarms in the same way.

In short, there is an acknowledgment field that holds a variable. When the variable is true, the text in the alarm display will clear out. For our example, we are going to add a button to the HMI. In short, your HMI should be modified to look like the following:

Figure 14.31 – HMI with Ack button

Figure 14.31 – HMI with Ack button

Once you add the button, add a variable called ack of type bool to the PLC_PRG file. We’re going to want to...