What serial port are you using to connect the Arduino to the Xbee?
What serial port are you using to connect the Arduino to the PC USB interface?
The same pins cannot be used for both functions at the same time.
What serial port are you using to connect the Arduino to the Xbee?
What serial port are you using to connect the Arduino to the PC USB interface?
The same pins cannot be used for both functions at the same time.