How to Program PLC Using Function Block Diagrams | OpenPLC

Introduction

This tutorial guides you through programming a PLC (Programmable Logic Controller) using Function Block Diagrams (FBD) with the OpenPLC editor. FBD is a powerful graphical programming method that simplifies the process of designing control systems. By the end of this guide, you will understand how to create and test FBDs through practical examples.

Step 1: Setting Up the OpenPLC Editor

• Download and install the OpenPLC editor from the official website.
• Launch the OpenPLC editor and create a new project.
• Familiarize yourself with the interface, which includes:
  • Toolbox: Contains various function blocks you can use.
  • Workspace: Area where you will design your FBD.
  • Properties Pane: Displays properties of selected blocks.

Step 2: Understanding Function Block Diagrams

• Learn the basic components of FBD:
  • Function Blocks: Represent logic operations (AND, OR, NOT, etc.).
  • Inputs and Outputs: Each block has input and output connections.
• Recognize how blocks can be interconnected to create complex logic.

Step 3: Creating Your First Function Block Diagram

• Drag and drop function blocks from the toolbox into the workspace.
• Connect blocks by clicking and dragging from the output of one block to the input of another.
• Example setup:
  • Start with an AND block.
  • Connect two input blocks to the AND block.
  • Connect the output of the AND block to a coil (output).

Step 4: Configuring Block Parameters

• Double-click on each block to open the properties pane.
• Set parameters such as:
  • Input names (e.g., switch inputs).
  • Output names (e.g., motor control).
• Ensure that all connections are properly defined.

Step 5: Testing Your Function Block Diagram

• Use the built-in simulation feature of the OpenPLC editor.
• Run the simulation to check if the logic behaves as expected.
• Manipulate input values to observe changes in the output.

Step 6: Saving and Uploading Your Project

• Save your project frequently to avoid data loss.
• Once satisfied with your FBD, export it for use on a physical PLC.
• Upload the project to your PLC using OpenPLC's upload feature.

Conclusion

You have learned how to create and test Function Block Diagrams using the OpenPLC editor. Key points include understanding the interface, creating and configuring blocks, and testing your logic. For more advanced FBD concepts, consider watching related tutorials on Function Block Diagrams. Start experimenting with your own control systems to further enhance your skills!