// PROGRAM : Bulb using Relay.

int R=8;

void setup()
{
    Serial.begin(9600);
    pinMode(R,OUTPUT);
}

void loop()
{
    if(Serial.available())
    {
        int b = Serial.read();
        if( b == 'O')
            digitalWrite(R,HIGH);
        else
            digitalWrite(R,LOW);
    }
}