int relayPin = 10;                // choose the pin for the LED
int inputPin = 2;               // choose the input pin (for PIR sensor)
int pirState = LOW;           
int val = 0;                    // variable for reading the pin status

void setup() {
  pinMode(relayPin, OUTPUT);      // declare LED as output
  pinMode(inputPin, INPUT);     // declare sensor as input

  Serial.begin(9600);
}

void loop() {
  val = digitalRead(inputPin);  // read input value
  if (val == HIGH) {            // check if the input is HIGH
    digitalWrite(relayPin, HIGH);  // turn Relay ON
    if (pirState == LOW) {
      pirState = HIGH;
    }
  } else {
    digitalWrite(relayPin, LOW);
    if (pirState == HIGH) {
      pirState = LOW;
    }
  }
}