Rework without the delay between each byte, eg.
const int ledPin = 13;
byte input1;
void setup()
{
Serial.begin(28800);
}
void loop()
{
while (Serial.available()) // while data is received
{
input1 = Serial.read();
if (input1 < 128) // just a check that I don't receive random crap
{
Serial.write(input1); // send the data back to check
}
}
// short delay *here* if you absolutely must
}