// The pins for the relay modules.
const int relay1Pin = 5;

void setup() 
{
  // Set pins as output.
  pinMode(relay1Pin, OUTPUT);

  delay(1000);
}

void loop() 
{
  
  digitalWrite(relay1Pin,HIGH); // Activate relay.
  delay(5000);
  digitalWrite(relay1Pin,LOW);  // Release the relay.
  delay(5000);

}