onoff

 int led = 2;
3.
4.  void setup()
5.  {
6.    Serial.begin(9600);
7.    pinMode(led, OUTPUT);
8.
9.  }
10.
11. void loop()
12. {
13.   char data = Serial.read();
14.
15.   switch(data){
16.     case 'ON': digitalWrite (led, HIGH);break;
17.     case 'OFF': digitalWrite(led, LOW); break;
18. }
19. }