Industrial IoT & Automation
Building Industrial IoT Telemetry Systems: Modbus RS485 to MQTT Cloud Gateways
BCNT Hardware & Firmware Team
July 30, 2026
6 min read
Learn how to bridge legacy plant machinery running RS485 Modbus RTU to modern MQTT cloud brokers using custom microcontrollers and encrypted Node-RED flows.
### The Architecture: RS485 Modbus to MQTT
To digitize plant operations without replacing million-dollar capital equipment, we deploy edge IoT telemetry gateways:
1. **Modbus Master Polling**: An embedded STM32 or ESP32 microcontroller polls slave PLC registers over RS485 differential lines (9600/115200 baud).
2. **Payload Parsing & JSON Formatting**: Raw integer values (temperature, current draw, vibration RMS) are parsed and packed into lightweight JSON strings.
3. **TLS Encrypted MQTT Transmission**: The gateway connects via cellular 4G or Wi-Fi to transmit JSON payloads over port 8883 to an EMQX or Mosquitto MQTT broker.
4. **Node-RED & Web Dashboard**: Incoming MQTT streams update real-time gauges, log database records in PostgreSQL, and trigger automated WhatsApp/SMS alerts when thresholds exceed safe limits.
Through custom PCB hardware design and low-latency MQTT architecture, BCNT Technologies enables factory managers in Pune, Chennai, and Coimbatore to monitor plant OEE in real time.
Related Engineering Insights
5-Axis CNC Machining Best Practices for Tight Tolerances in Aerospace Components
Explore how 5-axis simultaneous CNC milling eliminates multi-setup stackup errors, achieve...
Read MoreArchitecting Scalable Enterprise Web Applications with Laravel 11 and React
Best practices for pairing Laravel 11 RESTful backends with React frontend SPAs, implement...
Read More