Overview

Node-RED is an open-source, flow-based tool for wiring together hardware devices, APIs, and online services. Running it as a container on an ALPON X5 AI or ALPON X4 edge computer turns the device into a local automation gateway: it can poll PLCs and sensors on the factory floor, transform the data, and forward it to the cloud, all without a separate industrial PC.

With the Modbus palette added, Node-RED speaks Modbus TCP to any compatible device, energy meter, or PLC on the same network as the ALPON. The steps below are identical on ALPON X4 and ALPON X5 AI.

1. 1

   Add the Node-RED container

   Make sure the nodered/node-red image is available to your device. The recommended path is to push it to your Sixfab Registry so deployments are fast and work offline. From your build machine, pull the arm64 image:

   bash · pull the image

   docker pull --platform linux/arm64 nodered/node-red:latest

   Then log in to Sixfab Registry, click + Add Container, and follow the prompts to push the image.

   Pushing images to the Sixfab Registry

   For the full walkthrough of tagging and pushing an image, see Update Containers from the Sixfab Registry.

   Alternative: deploy straight from Docker Hub

   If you prefer not to use the Sixfab Registry, choose “I would like to use my own container path” during deployment and enter nodered/node-red:latest. The container is then pulled directly from Docker Hub (the device needs internet access at deploy time).

2. 2

   Deploy the container on ALPON

   Open your device in Sixfab Connect, go to the Application section, and click + Deploy. In the Deploy Container window, use these settings:

   Container Name node-red

   Image The Node-RED image and tag you pushed to the Sixfab Registry — or, using the alternative option, nodered/node-red:latest.

   Enable Host Network Turn this on so Node-RED can reach other devices — including your Modbus equipment — on the local network.

   

   Click + Deploy to launch Node-RED on the device.

3. 3

   Open the Node-RED editor

   Once the deployment finishes, find the device's local IP address under Asset Details → Network tab → Interface Monitoring → Details, then open the editor in a browser:

   browser · Node-RED editor

   http://<DEVICE_IP>:1880

   The Node-RED flow editor should now load. If it doesn't, confirm the container is running in the Application section and that Host Network was enabled in step 2.

4. 4

   Install Modbus support

   In the Node-RED editor, open the menu in the top-right corner and choose Manage Palette.

   

   Switch to the Install tab and search for node-red-contrib-modbus, then click Install.

   

   After the install completes, the Modbus nodes appear in the palette on the left.

5. 5

   Build a Modbus read flow

   Drag nodes from the palette to assemble a flow like the one below — a trigger feeding a Modbus-Read node, wired to a debug node so you can watch the values.

   

   Double-click the Modbus-Server node, configure it as shown, and click Done. This example uses port 10502 — use another port if your setup requires it.

   

   Next, double-click the Modbus-Read node to configure it. This example uses FC 3: Read Holding Registers, but you can pick a different function code to match your device.

   

   Click the + button next to the server field to define the Modbus server to read from. Fill in the required fields, click Add, then Done.

   

   Finally, click Deploy in the top-right corner and open the debug panel. If everything is configured correctly, you'll see register values arriving on the polling interval.

   

The Deploy Container window on Sixfab Connect, with Host Network enabled.

Open Manage Palette from the Node-RED menu.

Search for node-red-contrib-modbus and install it.

An example Modbus read flow.

Configuring the Modbus-Server node on port 10502.

The Modbus-Read node set to FC 3: Read Holding Registers.

Defining the Modbus server for the read node.

Modbus data arriving in the Node-RED debug panel.