I have an Arduino board with Intel Edison on it. I have tried to read data in Arduino from MatLab through the serial port. I'm sure the Arduino board is working because when I use the serial monitor from Arduino, it shows the data read from the Arduino board. My command is like this in Arduino:

   reading = Wire.read();
   Serial.println(reading)

I got errors in Matlab when I tried to work with these piece of code:

   s=serial('COM4');
   set(s,'BaudRate',9600);
   fopen(s);

MatLab complains that "Port: COM4 is not available. No ports are available. Use INSTRFIND to determine if other instrument objects are connected to the requested device." I have tried with "instrfind()" in matlab and got this:

   Instrument Object Array

   Index:    Type:     Status:   Name:  
   1         serial    closed    Serial-COM4
   2         serial    closed    Serial-COM4
   3         serial    open      Serial-COM4
   4         serial    closed    Serial-COM4
   5         serial    closed    Serial-COM4

I still can't get any clue on this. Can anybody help me?