Arduino and BV20 Bill Acceptor/Validator

I tried the serial protocol. But as said earlier, I'm very new to electronics.

I connected the BV20 output to arduino pin 0 (Rx pin) and wrote this code:

void setup()
{
  Serial.begin(9600);
 }

void loop()
{
  if( Serial.available() > 0)
  {    
    Serial.println(Serial.read());   
  }
}

When I put a bill in the validator, nothing outputs in the serial monitor.