Relais Module 5v High load capacity: AC250V 10A / DC30V 10A Relay control: 5V1-channel relay board

// Canonical example for a 5V 1-channel relay module
// The relay input is active-low:
//   LOW  = relay ON
//   HIGH = relay OFF

const int RELAY_PIN = 7;

void setup() {
  pinMode(RELAY_PIN, OUTPUT);

  Serial.begin(9600);
  while (!Serial) {
    ;
  }

  // Start with the relay turned off.
  digitalWrite(RELAY_PIN, HIGH);
  Serial.println("Relay module example started.");
  Serial.println("Sending LOW turns the relay ON, HIGH turns it OFF.");
}

void loop() {
  Serial.println("Relay ON");
  digitalWrite(RELAY_PIN, LOW);
  delay(1000);

  Serial.println("Relay OFF");
  digitalWrite(RELAY_PIN, HIGH);
  delay(1000);
}