# 5V relay module, serial control from PC, USB, CH340

> 5V relay module (ref. 9641) with serial control from a PC via USB, based on the CH340 chip. Powered directly from USB and controlled using serial debugging software at 9600 baud via hex frames (e.g. A0 01 01 A2 for ON). Features a status LED, 5V logic voltage, USB male 2.0 interface. Relay contacts rated up to 250VAC 10A (5A max recommended).

- Page: https://sigmanortec.ro/en/5v-relay-module-serial-control-from-pc-usb-ch340
- Price: 28.75 RON
- Availability: In stock; 1-2 zile
- Reference: 9641 · EAN: 5942133164974
- Category: Electronic components > Relays
- Specifications: Input Voltage: 5 V; Input Voltage Type: “DC” in Romanian can mean **“de ce”**, which translates to **“why”** in English.
- Package (shipping data): 0.016 kg
- Updated: 2026-09-23
- Shop: [Sigmanortec.ro](https://sigmanortec.ro/en/llms.txt)
- Prices: RON, VAT included; prices and stock as of 2026-10-22 05:21 (Europe/Bucharest)

## Description

Allows ON or OFF control of a relay directly from the PC via USB and serial communication, using CH340 and a serial debugging software. It is powered and connected simply from the 5V USB port, has LED to indicate the relay status, the command is done quickly through hex frames at 9600 baud. The relay contacts support up to 250VAC 10A for general automation and test applications.
Relay module with serial communication, with CH340, controllable directly through the serial port of the computer (with debug serial port software), which allows its ON or OFF control.
The board has an LED indicating relay status, on or off.
The module is connected and powered directly from the computer's USB port.
The board may be incompatible with the latest version of the CH340 driver (2023). Download the driver from the Download section.
Specifications:
Supply voltage: 5VDC, via USB
Relay: 250VAC, 10A (recommended 5A maximum to prevent contact welding)
Logic voltage: 5V
Communication IC: CH340
Interface: USB Tata 2.0
Use:
Install the CH340 driver and use a serial debugging software such as STC-ISP or SSCOM332. Set the baud rate to 9600 and send, in hexadecimal (hex) format "A0 01 01 A2" to activate the relay or "A0 01 00 A1" to deactivate the relay.
USB LC protocol:
Data (1) --- starting identity (the default is 0xA0)
Data (2) --- switch address code (default is 0x01, identifying the first channel switch)
Data (3) --- Operating Data (0x00 to "Off", 0x01 "On")
Date (4) --- checksum