The data is different RS232 Serial Data

If you check the serial receiver, you will see the following.

Why does it come out like this...

This is Arduino DUE. Only the Serial Port ( 1 ~ 3 ) side comes out like this.

Other Program Port or Native Port is output normally.

Arduino Program

void setup() { Serial2.begin(9600); }
void loop() { Now_03(); delay(500); }​

void Now_03()
Serial2.print(1); Serial2.print(2); Serial2.print(3); Serial2.print(4); Serial2.print(5);

comport set
9600 , None , 8 ,1

Recive Data

Expected data: 12345

Real Data : ????

What is the "serial receiver"? Is it a PC app? How have you connected the DUE to this "serial receiver" ?

It works fine on an Uno translated for Serial rather than Serial2.