arduino standalone

Good morning i use arduino mega 2560 first they run standalone without usb cable i use the normal serial port and serial port1 for comunicate to pc using usb arduino serail adapter at 115200 velocity first run without usb programming cable now not run without it how to use arduino standalone without the usb cable and only with power supply 12V? please help me thank you

Sorry, I am a newbee at this but isnt velocity meant to be 9600 baud??

Bit rate can be anything you like, as long as it is supported by the serial receiver

i have try with 9600 but not run first run wiht 115200 correctly when i send a character with terminal of windows i receive a not normal character when the usb calbe is disconnected when i connected run normal sorry for english

i use arduino 1.0.5 for compile
this is project

String inputString = “”; // a string to hold incoming data
boolean stringComplete = false; // whether the string is complete

void setup() {
// initialize serial:
Serial.begin(9600);
Serial1.begin(9600);
Serial.flush();
Serial1.flush();
// reserve 200 bytes for the inputString:
inputString.reserve(200);
}

void loop() {
// print the string when a newline arrives:
if (stringComplete) {
Serial1.println(inputString);
// clear the string:
inputString = “”;
stringComplete = false;
}
}

void serialEvent1() {
while (Serial1.available()) {
// get the new byte:
char inChar = (char)Serial1.read();
// add it to the inputString:
inputString += inChar;
// if the incoming character is a newline, set a flag
// so the main loop can do something about it:
if (inChar == ‘\n’) {
stringComplete = true;
}
}
}

i try this project with hyerterminal