ESP32 4-Channel Relay Module RS485 Modbus RTU Board
ESP32 4-Channel Relay Module RS485 Modbus RTU Board
ESP32 4-Channel Relay Module with RS485 & Modbus RTU Support
Take your automation and IoT projects to the next level with this versatile ESP32 Four-Channel Relay Module. Featuring built-in Wi-Fi and Bluetooth via the ESP32 microcontroller, RS485 communication, and full Modbus RTU protocol support, this development board is engineered for reliable, scalable control applications — from industrial automation to smart home systems.
Key Features
- ESP32 Microcontroller — Onboard Wi-Fi and Bluetooth connectivity for wireless control and IoT integration
- 4-Channel Relay Output — Control up to four independent circuits simultaneously with high-current relay switching
- Full Optocoupler Isolation — Both input and output sides are optocoupler-isolated, protecting your microcontroller and sensitive circuitry from high-voltage transients
- RS485 Interface with Modbus RTU Protocol — Industry-standard communication for long-distance, noise-resistant data transmission in professional environments
- Built-in CH340 Serial Port Chip — Seamless USB-to-serial conversion for easy programming and debugging via standard tools
- Flexible Power Input — Accepts 9–24V DC power supply as well as USB Type-C, giving you flexible installation options in the field or on the bench
- Compact Form Factor — Measures just 93mm × 87mm, making it easy to integrate into enclosures and project builds
Technical Specifications
| Microcontroller | ESP32 (Wi-Fi + Bluetooth) |
| Relay Channels | 4 |
| Communication | RS485 / Modbus RTU |
| Isolation | Optocoupler (Input & Output) |
| Serial Chip | CH340 |
| Power Input | 9–24V DC or USB Type-C |
| Board Dimensions | 93mm × 87mm |
| Voltage Classification | Low Voltage (Below 50V AC / 75V DC) |
| Country of Origin | Made in China |
What's in the Box
- 1× ESP32 4-Channel Relay Module (RS485 / Modbus RTU Development Board)
Ideal Applications
- Industrial automation and process control
- Smart home and building automation
- Remote switching and monitoring systems
- DIY electronics and IoT prototyping
- PLC-to-device communication bridges
Note: Due to lighting and display variation, colors may appear slightly different from product images. Please allow ±1–10mm dimensional tolerance due to manual measurement.
For guidance on safe handling of electrical and electronic development boards, refer to the U.S. Consumer Product Safety Commission – Electrical Safety Resources.
Frequently Asked Questions
Q: Does this ESP32 relay module support wireless programming over Wi-Fi?
A: Yes! The onboard ESP32 chip includes both Wi-Fi and Bluetooth, enabling over-the-air (OTA) firmware updates and wireless communication with IoT platforms and home automation systems.
Q: What is the purpose of optocoupler isolation on this relay board?
A: Optocoupler isolation electrically separates the control-side (your microcontroller or computer) from the relay-side (high-voltage loads). This protects sensitive components from voltage spikes and interference, improving reliability and safety in your projects.
Q: Can I use this board with both USB Type-C and DC power simultaneously?
A: The board supports 9–24V DC input as well as USB Type-C power. It is recommended to use one power source at a time; refer to your specific setup requirements and the board's power input circuitry before connecting both simultaneously.
Q: What software or libraries do I need to program this ESP32 Modbus relay board?
A: You can program it using the Arduino IDE with ESP32 board support installed, or using the ESP-IDF framework. For Modbus RTU, libraries such as ModbusMaster or ESP32 Modbus are commonly used. The built-in CH340 chip means most systems will recognize the board as a standard COM/serial port without additional drivers.