Optimized Bi-Directional Modbus Serial/RTU/RS485 to MQTT Gateway in Node-RED

Overview

This high-efficiency Node-RED flow creates a bi-directional bridge between Modbus Serial/RTU/RS485 devices and MQTT brokers, enabling real-time data collection and remote device control. Designed for minimal footprint and maximum flexibility, it supports industrial automation, IoT integration, and legacy system modernization.

Key Features

✅ True Bi-Directional Communication

• Read: Collect data from Modbus devices → publish to MQTT

• Write: Update Modbus registers via MQTT commands (for SCADA/dashboards)

✅ RAW Payload Support – Transfers data in raw format, ensuring minimal processing overhead and compatibility with various MQTT consumers.
✅ Scalable Architecture – Easily expandable to support multiple Modbus devices and multiple register mappings without complex modifications.
✅ Flexible Configuration – Customizable polling intervals, register addresses, and MQTT topics for tailored integration.
✅ Lightweight & Efficient

Demo & Tutorials

📺 Watch the Demo Video ( https://youtu.be/Mi_ZkUzipQQ )

Use Cases

• Industrial IoT: Real-time monitoring + control of PLCs, sensors, and meters

• Energy Management: Remote adjustment of power grid parameters via MQTT

• Smart Agriculture: Bi-directional communication with irrigation controllers

• Legacy System Integration: Modernize old Modbus equipment with MQTT cloud connectivity

Technical Specifications

• Protocols: Modbus RTU/RS485 (Serial) ↔ MQTT

• Payload Formats: RAW (default)

• Deployment: Runs on Node-RED (Windows/Linux/Raspberry Pi/Docker/Edge Devices).

• Extensible: Supports adding multiple Modbus slaves and register blocks

Why Choose This Solution?

• Plug-and-Play Setup – Pre-configured flow for quick deployment.

• Future-Proof – Easily adapts to new devices and tags

• Reliable & Lightweight – Optimized for stable, long-term operation.