How to Use 1 Channel USB Powered Relay Module (NL): Examples, Pinouts, and Specs

The 1 Channel USB Powered Relay Module (NL), manufactured by Numato Lab (Part ID: usbpowrl002), is a compact and versatile relay module designed for controlling high-voltage devices using a low-voltage USB signal. This module features a single relay channel, making it ideal for simple on/off control applications. It is USB-powered, eliminating the need for an external power supply, and is well-suited for automation, home appliances, and IoT projects.

• Home automation (e.g., controlling lights, fans, or appliances)
• Industrial equipment control
• IoT projects requiring remote switching
• Prototyping and educational purposes

The module has a USB interface for power and control, and a terminal block for connecting the load. Below is the pin configuration:

• NO (Normally Open): The circuit is open by default and closes when the relay is activated.
• NC (Normally Closed): The circuit is closed by default and opens when the relay is activated.
• COM (Common): The common terminal for the relay.

1. Connect the USB Cable:

   • Plug the module into a USB port on your computer or a USB power adapter. This provides both power and control signals.

2. Connect the Load:

   • Identify the type of load you want to control (e.g., a light bulb or motor).
   • Connect one terminal of the load to the COM pin and the other terminal to either the NO or NC pin, depending on the desired behavior:
     • Use NO if you want the load to turn on when the relay is activated.
     • Use NC if you want the load to turn off when the relay is activated.

3. Control the Relay:

   • Use the USB interface to send control signals to the relay. The module can be controlled using simple serial commands from a computer or microcontroller.

• Power Supply: Ensure the USB port or adapter provides sufficient current (at least 500mA) to power the module and the relay.
• Load Ratings: Do not exceed the maximum switching voltage (250V AC / 30V DC) or current (10A) to avoid damaging the relay.
• Isolation: The relay provides electrical isolation between the control circuit and the load, but additional safety precautions should be taken when working with high voltages.
• Software Control: The module can be controlled using serial commands via a terminal program or custom software. Refer to the manufacturer's documentation for detailed command syntax.

The module can be controlled by an Arduino UNO using a USB-to-serial adapter. Below is an example code snippet:

// Example code to control the 1 Channel USB Powered Relay Module (NL)
// using an Arduino UNO. This code sends serial commands to toggle the relay.

void setup() {
  Serial.begin(9600); // Initialize serial communication at 9600 baud
  delay(1000);        // Wait for the relay module to initialize
}

void loop() {
  // Turn the relay ON
  Serial.println("relay on"); // Send command to turn the relay ON
  delay(5000);               // Wait for 5 seconds

  // Turn the relay OFF
  Serial.println("relay off"); // Send command to turn the relay OFF
  delay(5000);                 // Wait for 5 seconds
}

Note: Replace "relay on" and "relay off" with the actual commands specified in the Numato Lab documentation if they differ.

1. Relay Not Activating:

   • Cause: Insufficient power supply or incorrect USB connection.
   • Solution: Ensure the USB port provides at least 500mA. Check the USB cable and connection.

2. Load Not Switching:

   • Cause: Incorrect wiring of the load to the relay terminal block.
   • Solution: Verify the load is connected to the correct pins (COM and NO/NC) based on the desired behavior.

3. Serial Commands Not Working:

   • Cause: Incorrect baud rate or command syntax.
   • Solution: Ensure the baud rate is set to 9600 and the commands match the manufacturer's documentation.

4. Overheating:

   • Cause: Exceeding the relay's maximum current or voltage ratings.
   • Solution: Check the load specifications and ensure they are within the relay's limits.

Q: Can I use this module with a Raspberry Pi?
A: Yes, the module can be controlled by a Raspberry Pi using its USB interface. Use Python's serial library to send commands.

Q: Is the relay module safe for high-voltage applications?
A: The relay is rated for up to 250V AC and 10A, but proper safety precautions must be taken when working with high voltages.

Q: Can I control multiple modules simultaneously?
A: Yes, multiple modules can be connected to different USB ports and controlled independently.

Q: Does the module require any drivers?
A: Most operating systems recognize the module as a standard USB device. If not, refer to the Numato Lab website for driver downloads.

Q: What is the lifespan of the relay?
A: The relay is rated for approximately 100,000 operations under normal conditions.