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Industrial ESP32 gateway: Modbus RTU to MQTT
RS-485 communication gateway for transparent conversion of Modbus RTU data into JSON-formatted MQTT topics for SCADA and MES.
#ESP32-S3#Modbus RTU#RS-485#MQTT#ArduinoJson#PlatformIO
Communication and architecture flow
Meter / PLC (Modbus RTU)Twisted-pair RS-485ESP32-S3 gatewayMosquitto MQTT brokerSCADA / MES
Industrial challenge / problem:
Legacy power meters and variable-frequency drives in an electrical panel communicate only through Modbus RTU over RS-485, preventing direct visualization in web systems.
Technical solution developed:
Build an embedded gateway with an ESP32-S3 and a galvanically isolated RS-485 transceiver. The gateway reads slave registers and publishes them over Wi-Fi or Ethernet to the Mosquitto broker and SCADA system.
Project component list:
- ESP32-S3 DevKitC-1 N8 module
- Isolated MAX485 / SP3485 RS-485 transceiver
- 24 V → 5 V DIN-rail industrial power supply
- 120 Ω termination resistor
Expected result in operation:
Update electrical parameters every second with high immunity to electrical noise and automatic reconnection.
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Install the environment, assemble the circuit, compile and validate it—with the complete firmware and PDF manual available to download.
Open the tutorial