Parallax RFID Reader module not sending tag-id to Arduino

Hello Guys!

We are four guys working on a projekt with the RFID Reader ( Blue ) and Arduino ( Leonardo ) . But our problem is when the Reader is connected to the Arduino and the RFID reader shows the RED light( ready ) we get absolutly nothing on our Arduino monitor. There are also a little light on the Arduino ( RX ) who should, but not doing it, light up when signal is received.

our code it :

const int startByte = 10;
const int endByte = 13;
const int tagLength = 10;
const int totalLength = tagLength + 2;
char tag[tagLength + 1];
long lastTagValue = 0;

int bytesread = 0;
void setup()
pinMode(2, OUTPUT);
digitalWrite(2, LOW);

void loop()
 if(Serial.available() >= totalLength)
 if( == startByte)
 bytesread = 0;
while(bytesread < tagLength) 
  int val =;
  if((val == startByte)||(val == endByte))
  tag[bytesread] = val;
  bytesread = bytesread + 1;
if( == endByte)
  tag[bytesread] = 0;
  long tagValue = atol(tag);
  Serial.print("RFID tag is: ");
  lastTagValue = tagValue;

We hope someone can help see the problem

// Simon

The USART (serial) interface of the Leonardo is available by the Serial1 object, the Serial object is for the connection to the PC (USB, debugging).

Apart from that problem, you should never attempt to read more characters, than the number which is available.

If you get one character arrive on the serial, you then go and try to read a whole bunch of characters. This won't work

you should never attempt to read more characters, than the number which is available.

The OP is not doing that (if(Serial.available() >= totalLength)). But he's waiting until the total number of characters arrived, which is never a good idea in a serial protocol (you might have missed one character).

Found solution!

Changede the RX-pin to another.