4-Channel RS232 Relay Control Board DC9-30V | Smart Switch

4-Channel RS232 Serial Port Relay Control Board — DC9-30V Computer-Controlled Switch Module

Take full command of your electrical devices from your computer with this industrial-grade 4-Channel RS232 Serial Relay Control Board. Simply connect via serial cable, install the driver, and use the upper-computer software to toggle motors, lights, heating elements, fans, and more — all with a single mouse click, no need to be on-site. Made in Mainland China.

Key Features

• 4 Independent Relay Channels — control up to four separate devices simultaneously with full electrical isolation between channels.
• Industrial-Grade EMI Protection — professional anti-electromagnetic interference circuit design built for demanding environments with high electrical noise.
• Complete Electrical Isolation — the controller is fully isolated from the electrical load; each I/O channel is independently isolated from its output, eliminating cross-channel interference.
• Status Indicator LEDs — each relay output features a dedicated indicator light for instant, at-a-glance monitoring of operating status.
• Reverse-Polarity Protection — built-in safeguard prevents damage from accidental reverse power connections.
• High Current Capacity — reinforced copper-strip traces on the PCB back ensure reliable passage of large currents, maintaining stability under load.
• Dual Delay Modes — each channel supports two software-selectable delay modes, configurable directly from your computer.
• Compact Surface-Mount Design — SMD components deliver efficient heat dissipation and a dense, reliable layout suited for integration into panels or enclosures.

Specifications

Applications

• Smart Home Automation
• Internet of Things (IoT) Control Systems
• Industrial Process Control
• Electric Motor Drive & Switching
• Remote Monitoring & Management Systems

Important Notes

• Ensure the USB-to-serial port driver is correctly installed before use; the device should appear without error flags in Device Manager.
• If the software is unresponsive, try reinserting the USB-to-232 serial cable.
• Do not operate this module beyond the rated power supply and load parameters.
• Slight color variation from product images may occur due to screen settings. Dimensions may vary by 1–10 mm due to manual measurement.

Package Includes

• 1× 4-Channel RS232 Relay Control Board
• 1× Cable

For additional guidance on electrical safety when working with relay control systems, refer to OSHA's Electrical Safety Resources.

Frequently Asked Questions

Q: What power supply do I need for the 4-channel RS232 relay control board?

A: This relay module accepts a DC power supply in the range of 9V to 30V. Make sure your power source falls within this range to ensure stable, safe operation. Always stay within the specified voltage and current parameters.

Q: What is the maximum load I can switch with each relay channel?

A: Each of the four relay channels can handle up to AC 250V / 10A or DC 30V / 10A. This makes it suitable for switching motors, lighting, heating elements, fans, and other standard electrical loads within those ratings.

Q: How do I connect and control this relay board from my computer?

A: Connect the board to your PC using a USB-to-RS232 serial cable. Install the required USB-to-serial port driver so the device is recognized in Device Manager. Once connected, use the included upper-computer software to switch each relay channel on or off and configure delay modes — all from your desktop with a mouse click.

Q: Can this relay module be used for smart home and IoT automation projects?

A: Yes. The 4-channel RS232 relay control board is well-suited for smart home automation, IoT applications, industrial control systems, and remote monitoring setups. Its isolated channel design and industrial-grade EMI protection make it reliable across a wide range of automation scenarios.