How using a arduino in LabView to show the FFT of a sensor output voltage signal (NEED HELP)

[emepecuatro]

I created code to show the FFT of an output signal of a sensor digitalized  by arduino. And it works fine but it works when I connect physically the sensor which is good. But I cannot prove how it works without it , I want someone to help me find a way to test my code with kind of signal generator VI that can be used to se how precise my code works. Yes it does work. 

This is the codeWhen I connect the sensor (+ arduino) it worsk showing the FFT in "real time"

By the way the code I use for the arduino is the following:

void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
}

void loop() {
  Serial.println(analogRead(A0));
}

and the sensor I connect is a hall sensor and I move a magnet in a oscillatory way. please your help!! 

Need to find a way in code to prove that the VI works.And what is measuring is right. Any question or specific idea let me know. I tried everything but i find lots of problems related to incoherencies with the data type and among others.