Data relay between two USARTs of an Arduino

SerialRelay.ino

#include <SoftwareSerial.h>

SoftwareSerial mySerial = SoftwareSerial(10, 11);; // RX, TX

void setup() {
  pinMode(10,INPUT);
  pinMode(11,OUTPIT);
  mySerial.begin(19200);// this connects to the other USART device
  Serial.begin(19200);  // this one connects to a computer via USB
  while (!Serial) {
    ; // wait for serial port to connect. Needed for Leonardo only
  }
} 

void loop() { 
  if (mySerial.available() > 0) {
    // relay everything received from mySerial to Serial    
    Serial.write(mySerial.read()); 
  }
  if (Serial.available() > 0) {
    // relay everything received from Serial to mySerial
    mySerial.write(Serial.read());        
  }  
}