Arduino passthrough serial

serial.ino

#include <SoftwareSerial.h>

#define RX_PIN 9
#define TX_PIN 10

SoftwareSerial printer = SoftwareSerial(RX_PIN, TX_PIN);

void setup() {
  Serial.begin(9600);
  printer.begin(19200);
  
}

int incomingByte = 0;

int cnt = 0;

void loop() {
  
  if(Serial.available() > 0) {
    incomingByte = Serial.read();

    // Forward bytes to printer
    Serial.println(incomingByte, HEX);
    printer.write(incomingByte);
    
    if(printer.overflow()) {
      Serial.println("SoftwareSerial buffer overflow!");
    }
    
    //Serial.println(printer.read(), HEX);
    
  }
}

Was using this to sleep at regular intervals, because the serial buffer on the receiving end had problems with the dataflow