Building a Universal Industrial Protocol Gateway with Node-RED — A Multi-Protocol Integration Solution Supporting Modbus, OPC UA, and MQTT

As industrial automation and the Industrial Internet of Things (IIoT) continue to advance, the diversity of field devices and communication protocols has increased significantly. Protocols like Modbus, OPC UA, and MQTT serve distinct layers: field devices, control and monitoring, and cloud/IT platforms, respectively. The isolation between these protocols has become a major bottleneck hindering system interoperability.

In this context, a universal industrial protocol gateway built on Node-RED is emerging as an efficient solution for multi-protocol fusion and data integration at the edge.

Challenges in Industrial Protocol Integration

Typical industrial systems often include:

• Sensors, meters, and PLCs accessed via Modbus RTU/TCP
• SCADA, MES, or HMI systems based on OPC UA
• Cloud platforms and data hubs communicating via MQTT

Traditional approaches rely on dedicated gateways or custom development, leading to issues such as:

• Fixed functionality with limited scalability
• Complex integration and high maintenance costs
• Tight coupling between OT and IT systems, hindering long-term evolution

Thus, a flexible, extensible, and easy-to-maintain universal protocol gateway has become essential infrastructure for industrial digital upgrades.

Node-RED: A Low-Code Protocol Orchestration Platform for Industry

Node-RED is a flow-based, low-code development tool that enables visual data acquisition, processing, and forwarding—making it ideal as the core engine for industrial protocol gateways.

Key advantages in industrial applications:

• Visual flow editing, significantly lowering the engineering barrier
• Rich node ecosystem supporting mainstream industrial and IoT protocols
• Event-driven architecture suited for real-time data handling
• Deployable on industrial-grade ARM edge devices for high reliability

Engineers can achieve complex protocol conversions without extensive coding.

Supported Core Protocols

• Modbus: Foundational Protocol for Field Devices Node-RED's Modbus nodes support both RTU and TCP modes for data acquisition from various devices.
  • RS485 and Ethernet communication
  • Applicable to meters, sensors, inverters, and PLCs
  • Enables polling, parsing, and data standardization
• OPC UA: Unified Data Access Interface Node-RED can function as an OPC UA Client or Server, building a standardized data access layer.
  • Integrates multi-source data into a standard OPC UA model
  • Facilitates connection to SCADA, MES, and industrial software
  • Enhances interoperability and security
• MQTT: Bridge to Cloud and Data Platforms MQTT is a lightweight messaging protocol widely used in IIoT, with native Node-RED support.
  • Publish/subscribe model
  • Ideal for low-bandwidth, remote scenarios
  • Seamless integration with cloud and IoT platforms

System Architecture

The Node-RED-based gateway employs a layered, decoupled architecture:

• Southbound Interface (OT Layer): Modbus RTU/TCP for field devices and controllers
• Edge Processing Layer: Node-RED Flows for data parsing, mapping, filtering, alarming, and logic processing
• Northbound Interface (IT Layer): OPC UA for SCADA/MES; MQTT for cloud and data services

This design achieves protocol decoupling and data standardization, providing a solid foundation for future expansions.

Advantages of Deployment on ARM Industrial Gateways BL118

Running Node-RED on ARM-based industrial gateways or embedded controllers maximizes edge computing benefits:

• Low power consumption and fanless design for harsh industrial environments
• Abundant industrial interfaces (RS485, Ethernet, CAN, DI/DO)
• Edge-side processing to reduce cloud communication load
• Rapid deployment and maintenance, shortening project timelines

The "Node-RED + ARM Gateway" combination is widely applied across industries.

Typical Application Scenarios

• Building automation: Aggregating data from multiple Modbus devices and uploading via MQTT
• Water treatment and environmental monitoring: Providing unified OPC UA interfaces to SCADA
• Energy management: Centralized meter data collection and analysis
• Remote equipment maintenance and condition monitoring

Conclusion

The Node-RED-based universal industrial protocol gateway offers a low-code, highly flexible, and sustainable solution for protocol integration. It effectively bridges the gaps between Modbus, OPC UA, and MQTT, laying a strong foundation for edge computing, cloud-edge collaboration, and industrial digital transformation.

In an era of deepening OT-IT convergence, Node-RED is becoming a vital bridge connecting the operational and information worlds.