2-Channel Ethernet Relay Module Modbus RTU W5500 STM32 DC7-36V
2-Channel Ethernet Relay Module Modbus RTU W5500 STM32 DC7-36V
2-Channel Ethernet Relay Module — Modbus RTU, W5500 TCP Server, STM32 Board
Take full remote control of your electrical switching applications over a standard LAN with this robust 2-Channel Ethernet Relay Module. Built around a stable 32-bit STM32F103C6T6 MCU and the hardware-accelerated W5500 Ethernet chip, this module delivers reliable Modbus RTU communication over TCP/IP — making it ideal for industrial automation, smart home projects, DIY electronics, and remote switching systems. Made in Mainland China.
Key Features
- STM32F103C6T6 MCU: Mature, stable 32-bit microcontroller ensures consistent performance and fast response times.
- W5500 Ethernet Chip: Full hardware TCP/IP protocol stack with 10/100 Mbps support — no software TCP overhead, maximum reliability.
- Modbus RTU Protocol: Fully compatible with the standard Modbus RTU protocol for seamless integration with PLCs, SCADA systems, and automation software.
- TCP Server Mode with DHCP: Operates as a TCP Server on port 5000; supports DHCP for automatic IP assignment. View IP address via serial port (UART baud rate: 115200).
- 2 Independent Relay Channels: Each relay rated at 10A/250VAC or 10A/30VDC, capable of 100,000 continuous switching cycles with diode discharge protection for long service life.
- Flexible Switching Modes: Supports manual, flashing on-off, and flashing off modes. Flashing delay base is 0.1 seconds; maximum configurable time: up to 6,553.5 seconds (0xFFFF × 0.1s).
- Configurable Device Address: Range 1–255 (default: 255) with power-off memory saving.
- Wide Input Voltage Range: DC 7–36V input via 5.08mm terminal block, with built-in reverse-polarity input protection.
- Onboard Indicator Lights: Dedicated LEDs for power status and each relay channel for at-a-glance monitoring.
- Secondary Development Ready: Reserved UART serial port and SWD programming port allow custom firmware flashing and advanced development.
- Onboard MCU Reset Button: Convenient hardware reset without disconnecting power.
Technical Specifications
| MCU | STM32F103C6T6 (32-bit) |
| Ethernet Chip | W5500 (Hardware TCP/IP Stack) |
| Network Speed | 10/100 Mbps |
| Protocol | Modbus RTU over TCP |
| TCP Port | 5000 |
| UART Baud Rate | 115200 |
| Relay Channels | 2 |
| Relay Rating | 10A/250VAC, 10A/30VDC |
| Relay Endurance | 100,000 switching cycles |
| Input Voltage | DC 7–36V |
| Connector | 5.08mm terminal block |
| Device Address | 1–255 (default 255, power-off saving) |
| Country of Origin | Made in Mainland China |
What's in the Box?
- 1× 2-Channel Ethernet Relay Module (STM32 + W5500)
Safety & Standards Reference
For guidance on electrical safety standards relevant to relay modules and industrial control equipment, visit the OSHA Electrical Safety resource page.
Frequently Asked Questions
Q: What communication protocol does this 2-channel Ethernet relay module support?
A: This module supports the standard Modbus RTU protocol over TCP/IP. It operates as a TCP Server on port 5000, using the W5500 hardware TCP/IP stack chip for highly reliable LAN-based relay control without software TCP overhead.
Q: What is the input voltage range and power connector type for this STM32 relay module?
A: The module accepts a wide DC 7–36V input voltage range, making it compatible with a variety of power supplies. It uses a 5.08mm terminal block connector and includes built-in reverse-polarity input protection to safeguard the board from accidental miswiring.
Q: Can I use this relay module for custom firmware or secondary development?
A: Yes. The board features a reserved UART serial port and an SWD program burning port, enabling developers to flash custom firmware and extend functionality for specialized automation or IoT applications.
Q: How do I find the IP address assigned to the relay module after connecting it to a LAN?
A: The module supports DHCP for automatic IP assignment. You can view the assigned IP address via the onboard UART serial port at a baud rate of 115200 using any standard serial monitor or terminal application.