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Patterns of Ladder Logic Programming

If you’re familiar with PC programming in languages like Java or C#, then you’ll probably know about the books Design Patterns: Elements of Reusable Object-Oriented Software and Patterns of Enterprise Application Architecture. These books are about Software Design Patterns.

As a long time ladder logic programmer, I thought one way to share my experience with newer programmers is to organize a list of common patterns used in ladder logic programming. This list of ladder logic programming patterns serves two purposes: first, each pattern is a tool for solving a common problem using ladder logic, and having these patterns in your toolbox will allow you to program faster and spend more time focusing on the higher level structure of your program. Second, since these are common patterns, you’ll start to find it easier to read other people’s ladder logic, and other experienced programmers will find it easier to follow your logic.

  1. The Sealed in Coil pattern
  2. The State Coil/Fault Coil pattern
  3. The Start/Stop Circuit pattern
  4. The Set/Reset pattern
  5. The Flasher pattern
  6. The Debounce pattern
  7. The Input Map pattern
  8. The Step pattern
  9. The Mission pattern
  10. The Five Rung pattern
  11. The Mode pattern


  • eplc · November 13, 2015 at 9:26 am

    I do think this is a great idea. Keep posting!

  • codezs09 · February 6, 2016 at 12:58 pm

    Very useful. Thank you for sharing

  • Cheng · February 15, 2016 at 10:29 am

    Very useful and detailed

  • LKH · March 8, 2016 at 8:29 am

    Very nice idea for people just starting out!
    You should include an Anti-Tie Down pattern 🙂

  • Bob · June 24, 2016 at 3:45 pm

    Very nice. I hope you keep adding new sections to this. Naming conventions, Fault – Acknowledgement pattern, Messages/Warnings/Alarms ect.

    I will be sharing this with my colleagues.

  • narakirin · November 28, 2016 at 1:43 am

    Thank you very much

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