int count = 0;
char card_no[12];
void setup()
{
   Serial.begin(9600);
}

void loop()
{
   if(Serial.available())
   {
      count = 0;
      while(Serial.available() && count < 12)
      {
         card_no[count] = Serial.read();
         count++;
         delay(5);
      }
      Serial.println(card_no);
   }
} 
