Designed by Namnam in Vietnam, the ESP32 Modbus gateway is built to communicate with PLCs and industrial sensors over Modbus RTU (RS-485) or Modbus TCP/IP (Ethernet/Wi-Fi). Designed for use in farms, factories, and electrical cabinets where reliable communication, remote monitoring, and control are required.
Key features of this industrial IoT board include Modbus RTU/TCP master and slave support, automatic Wi-Fi/Ethernet switching, multi-Wi-Fi handling, watchdog timer, deep sleep, and FOTA updates via FTP. The board supports a wide input voltage range and can be programmed over USB.
ESP32 Modbus gateway specifications
- Wireless Module – ESP32-WROOM-32 module with ESP32 dual-core processor @ 160 MHz, 520 Kbytes SRAM, 4 Mbit Flash
- Connectivity
- 10/100Mbps Ethernet RJ45 port via LAN8720A controller
- Wifi and WiFi 802.11 b/g/n, Bluetooth 4.2 via ESP32
- RS485 – SP485EE transceiver (Serial2, auto DERE)
- USB – USB Type-C port for programming and power
- Misc
- Onboard Red, Blue, and Pwr LED
- User and Reset buttons
- Buzzer for notifications
- Watchdog timer support
- Deep sleep mode
- Power supply
- 5V to 35V DC input
- MC34063A DC-DC converter,
- Dimensions – Not mentioned
In terms of software support, the ESP32 Modbus RTU/TCP device includes open-source Arduino code examples on GitHub for Modbus RTU/TCP (master and slave), MQTT, FOTA updates, watchdog, deep sleep, and auto Wi-Fi/Ethernet switching.
We have previously written about similar devices like the eModGATE Moduino X0 ESP32-based IoT controller with RS-232, RS-485, and various I/Os, and the MiniLink IIoT Node Arduino-compatible board with an RS-485 interface for sensors or actuators and a DIN rail mount for industrial environments. However, neither supports Ethernet and only relies on WiFi for Modbus RTU/TCP, although the eModGATE Moduino X0 is a complete device with a wider range of wireless options, namely LoRa, Sigfox, and/or LTE-NB/Cat.M1, and an enclosure.
Namnam sells the ESP32-based Modbus gateway on his Tindie store for $35.00 per unit. However, you can get bulk discounts of $29 for 20–49 units, and the price decreases to $25 for 50 units or more.
Debashis Das is a technical content writer and embedded engineer with over five years of experience in the industry. With expertise in Embedded C, PCB Design, and SEO optimization, he effectively blends difficult technical topics with clear communication
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