How to Use Gravity: Digital 16A Relay Module: Examples, Pinouts, and Specs

The Gravity: Digital 16A Relay Module (Manufacturer Part ID: DFR0251) by DFROBOT is a versatile and reliable relay module designed to control high-voltage devices using low-voltage digital signals. With a maximum current handling capacity of 16A, this module is ideal for applications in home automation, industrial control systems, and IoT projects. Its compatibility with microcontrollers like Arduino makes it a popular choice for hobbyists and professionals alike.

• Home automation (e.g., controlling lights, fans, or appliances)
• Industrial equipment control
• IoT-based smart systems
• Robotics and automation projects
• High-power device switching

Below are the key technical details of the Gravity: Digital 16A Relay Module:

The module has a simple pin layout for easy integration into your projects:

1. Power the Module: Connect the VCC pin to a 5V DC power source and the GND pin to ground.
2. Control Signal: Connect the Signal (S) pin to a digital GPIO pin of your microcontroller (e.g., Arduino).
3. Load Connection:
   • For devices that should remain off by default, connect them to the NO (Normally Open) terminal and COM terminal.
   • For devices that should remain on by default, connect them to the NC (Normally Closed) terminal and COM terminal.
4. Trigger the Relay: Send a HIGH signal (5V) to the Signal (S) pin to activate the relay and switch the connected device.

• Isolation: Ensure proper electrical isolation between the high-voltage side (load) and the low-voltage control side to prevent damage to your microcontroller.
• Current Rating: Do not exceed the maximum current rating of 16A to avoid overheating or damage to the relay.
• Flyback Diode: If controlling an inductive load (e.g., motors), use a flyback diode across the load to protect the relay from voltage spikes.
• Secure Connections: Use proper connectors or soldering to ensure secure and reliable connections.

Below is an example of how to use the Gravity: Digital 16A Relay Module with an Arduino UNO to control a light bulb:

• Connect the Signal (S) pin of the relay module to Arduino digital pin 7.
• Connect the VCC pin of the relay module to the 5V pin on the Arduino.
• Connect the GND pin of the relay module to the GND pin on the Arduino.
• Connect the light bulb to the NO and COM terminals of the relay module.
• Power the Arduino and the relay module.

// Define the relay pin
const int relayPin = 7;

void setup() {
  // Set the relay pin as an output
  pinMode(relayPin, OUTPUT);
  
  // Ensure the relay is off at startup
  digitalWrite(relayPin, LOW);
}

void loop() {
  // Turn the relay on (light bulb ON)
  digitalWrite(relayPin, HIGH);
  delay(5000); // Keep the light ON for 5 seconds
  
  // Turn the relay off (light bulb OFF)
  digitalWrite(relayPin, LOW);
  delay(5000); // Keep the light OFF for 5 seconds
}

1. Relay Not Switching

   • Cause: Insufficient trigger voltage or incorrect wiring.
   • Solution: Ensure the Signal (S) pin receives a voltage between 2.5V and 5V. Double-check all connections.

2. Load Not Turning On/Off

   • Cause: Incorrect connection to the NO, NC, or COM terminals.
   • Solution: Verify the load is connected to the correct terminals based on your desired behavior (normally open or normally closed).

3. Overheating

   • Cause: Exceeding the maximum current rating of 16A.
   • Solution: Ensure the load current does not exceed 16A. Use a heat sink or cooling mechanism if necessary.

4. Microcontroller Resetting

   • Cause: Voltage spikes from inductive loads.
   • Solution: Add a flyback diode across the load to suppress voltage spikes.

Q1: Can I use this relay module with a 3.3V microcontroller?
A1: Yes, the relay can be triggered with a voltage as low as 2.5V. However, ensure the VCC pin is still powered with 5V.

Q2: Is the module safe for controlling AC appliances?
A2: Yes, the module can handle up to 250V AC at 16A. Ensure proper insulation and safety precautions when working with high-voltage AC.

Q3: Can I control multiple relays with one Arduino?
A3: Yes, you can control multiple relay modules by connecting each Signal (S) pin to a separate GPIO pin on the Arduino.

Q4: What happens if I exceed the current rating?
A4: Exceeding the 16A current rating can damage the relay and may pose a fire hazard. Always stay within the specified limits.

By following this documentation, you can effectively integrate the Gravity: Digital 16A Relay Module into your projects for safe and reliable high-power device control.