Saving Issue(Maybe?).

DrAzzy, I added the function as you suggested. I then unplugged the board from the USB port and plugged the board back into the USB port, but the code does not seem to execute upon startup. My new code is:

var phValue="";

Serial4.setup(38400);
//Serial1.setup(9600/*baud*/);

Serial4.onData(function (e) {
  phValue+=e.data;

  if (e.data == "\r") {
    print(phValue);
    phValue="";
  }
});

function getPhValue() {
 on = !on;
 digitalWrite(LED1, on);

 Serial4.print("r\r");
}

function onInit() {
	var interval = setInterval(getPhValue, 1500);
}