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PLCs for Beginners

You're reading from   PLCs for Beginners An introductory guide to building robust PLC programs with structured text

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Product type Paperback
Published in May 2024
Publisher Packt
ISBN-13 9781803230931
Length 380 pages
Edition 1st Edition
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Author (1):
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M. T. White M. T. White
Author Profile Icon M. T. White
M. T. White
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Toc

Table of Contents (25) Chapters Close

Preface 1. Part 1: Basics of Computer Science for PLC Programmers
2. Chapter 1: Computer Science Versus Automation Programming FREE CHAPTER 3. Chapter 2: PLC Components – Integrating PLCs with Other Modules 4. Chapter 3: The Basics of Programming 5. Chapter 4: Unleashing Computer Memory 6. Chapter 5: Designing Programs – Unleashing Pseudocode and Flowcharts 7. Chapter 6: Boolean Algebra 8. Part 2: Introduction to Structured Text Programming
9. Chapter 7: Unlocking the Power of ST 10. Chapter 8: Exploring Variables and Tags 11. Chapter 9: Performing Calculations in Structured Text 12. Chapter 10: Unleashing Built-In Function Blocks 13. Chapter 11: Unlocking the Power of Flow Control 14. Chapter 12: Unlocking Advanced Control Statements 15. Chapter 13: Implementing Tight Loops 16. Part 3: Algorithms, AI, Security, and More
17. Chapter 14: Sorting with Loops 18. Chapter 15: Secure PLC Programming – Stopping Cyberthreats 19. Chapter 16: Troubleshooting PLCs – Fixing Issues 20. Chapter 17: Leveraging Artificial Intelligence (AI) 21. Chapter 18: The Final Project – Programming a Simulated Robot 22. Assessments 23. Index 24. Other Books You May Enjoy

Logical operators

In automation, it is very common for multiple conditions to be met before a system can perform a task. For example, in some cases, we may need to ensure that all the safety switches are open and the start button is engaged before the machine can start up. In other cases, we may need two motor drives to be on before the machine can try to move. To accomplish this, we need to look at more complex logical expressions.

So far, we have seen some code (nested IF statements) that will behave in such a way that multiple conditions need to be met before a certain task can be carried out. Nested states are suitable when some code needs to be executed based on a single condition while other code requires an extra condition to be satisfied. However, for many cases where all the code needs to be executed when multiple conditions are met, the nested statements can be cumbersome and bloat the code. This is mainly because all of our IF or ELSIF statements have only been used as...

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