SoftwareSerialPassthrough2.ino

#include <SoftwareSerial.h>

//                      RX,TX on Arduino
SoftwareSerial mySerial(8, 9);

void setup()
{
  Serial.begin(38400);
  mySerial.begin(38400);
}

void loop()
{
  /* send everything received from the hardware uart to usb serial & vv */
  if (Serial.available() > 0) {
    Serial.print("Sent: ");
    while( Serial.available() > 0 ){
      char ch = Serial.read();
      Serial.print(ch);
      mySerial.print(ch);
    }
  }
  
  if (mySerial.available() > 0) {
    char ch = mySerial.read();
    if( ch ){
      Serial.print(ch);
    }
  }
}