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CODESYS Example: RevPi CODESYS and Node-RED

Introduction​

This example demonstrates how to exchange I/O data between a RevPi CODESYS application and an external Node-RED application using a RevPi virtual device.

Prerequisites​

Hardware Requirements​

  • 1 RevPi Connect

Software Requirements​

  • CODESYS Development System installed on your PC
  • Node-RED and RevPi Nodes Server enabled.

If you are using the full image, Node-RED is already pre-installed. If you are using the lite image, Node-RED is not pre-installed. You can install Node-RED according to the instructions at the following link: Running on Raspberry Pi: Node-RED.

  • Web browser (for accessing the Node-RED interface and PiCtory)

Preparation​

Hardware Setup:​

Tipp: For detailed instructions about how to set up your system, refer to the Getting Started guide.

Software Setup:​

note: To ensure a compatible system with suitable software, please refer the following links:

Overview​

We use CODESYS Control for Linux Arm/ARM64 and Node-RED RevPi Nodes Server on a RevPi Connect. The CODESYS application includes a virtual RevPi device with 32-byte inputs and outputs that interact with a Node-RED application via the Node-RED RevPi Nodes Server.

Step 1: Create a Basic Flow in Node-RED​

▷ Start Node-Red

▷ Run the following command on Terminal to install the node-red-dashboard package:

npm install node-red-dashboard

Alternatively you can install node-red-dashboard by performing the following steps:

▷ Select the Manage palette option in the Node-RED Dashboard menu.

Node-red Dashboard

▷ Select the Install tab.

▷ Click install for the node-red-dashboard node.

Node-red Dashboard

➜ A number of nodes are now available in Node-RED that you can use to create a real-time data dashboard. You can find them on the Nodes tab.

Step 2: Import the "RevPi CODESYS Node-RED.json" Flow in Node-RED​

▷ Select the Import menu item

Node-red Dashboard

▷ Click on select a file to import and open the file RevPi CODESYS Node-RED.json in the Examples directory.

▷ To create the project as a new flow, select for Import to the new flow button.

▷ Select the Import button.

Node-red Dashboard

▷ To launch the application on the Node-RED server, select the De-ploy button.

Node-red Dashboard

Step 3: Setting Up the CODESYS Project​

▷ Create the RevPi CODESYS Node-RED project from the Examples directory and download it to the RevPi Connect running CODESYS Control for Linux ARM SL and Node-RED RevPi Nodes Server.

CODESYS

Application Functionality​

  1. CODESYS to Node-RED Data Flow:

    • The CODESYS application writes the values [1 ... 32] to the 32 output bytes (Q_Virtual) of the virtual RevPi device.

  2. Node-RED to CODESYS Data Flow:

    • The Node-RED application reads these 32 input bytes from the virtual RevPi device's address space.
    • It then writes them back to the output address space of the virtual RevPi device.

  3. Visualizing Data:

    • In CODESYS Online Mode:
      • The values can be observed under I_Virtual inputs in the Revolution PI Virtual Device I/O Mapping tab.
    • In Node-RED Application:
      • Connection status and values are displayed next to each revpi-getpin.

➜ The Node-RED application displays the connection status and value next to each revpi-getpin.

Node-red