#define RxOut D7
#define TxOut D6

HardwareSerial PortOut(1);

void setup() {
  Serial.begin(921600);

  PortOut.begin(921600, SERIAL_8N1, RxOut, TxOut);
}

void loop() {
  if (Serial.available()) {
    byte incoming = Serial.read();
    PortOut.write(incoming);
  }

  if (PortOut.available()) {
    byte incoming = PortOut.read();
    Serial.write(incoming);
  }
}