My Bluetooth connection between Arduino and Matlab is almost working.

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Hi guys

I have a problem with my bluetooth connection. I hope you can give me an advice on how to proceed.
I have 4 force sensors hooked up to an Arduino Pro Mini and a bluetooth HC-05. The sensors are being recorded in Matlab and works fine the first time.

The problem is that I have to cut the power to the Arduino and Bluetooth each time, if I dont cut the power this error comes:

Error using icinterface/fopen (line 83)
Unsuccessful open: Cannot connect to the device. Possible reasons are another application
is connected
or the device is not available.

Error in BT_Arduino_Saal_2 (line 6)
fopen(arduino);

I have tried to clear all, close and open the Arduino in Matlab before running the script again, but the same error keeps coming until I restart the system.

This is my Matlab code:

clear all;
clc;

instrhwinfo('Bluetooth');
arduino = Bluetooth('HC-05',1);
fopen(arduino); 

x=linspace(1,100); % 100 samples are recorded

numcols = 1; %1 coloum with data is made
y = {}; %All data are placed in y
for i=1:length(x);    
	data =fscanf(arduino,'%f'); % '%f' makes it decimals
     IncomingString = char(data); % the incoming data is turned to characters
     IncomingString = regexp(IncomingString, '\s*', 'split'); % data are split up, and in coloums
       Heel(i,1)= IncomingString(1,3); %#ok<SAGROW> % read data from coloum 3
       Metatars(i,1)= IncomingString(1,5); 
       Svang(i,1)= IncomingString(1,7); 
       Calcaneus(i,1)= IncomingString(1,9);
     
     
end

fclose(arduino);

PlotHeel = str2double(Heel); %Turn data from cell array to double data
figure(1)
plot(PlotHeel);
title('Heel'); xlabel('Samples'); ylabel('Volt');

PlotMetatars = str2double(Metatars); 
figure(2)
plot(PlotMetatars);
title('Metatars'); xlabel('Samples'); ylabel('Volt');

PlotSvang = str2double(Svang); 
figure(3)
plot(PlotSvang);
title('Svang'); xlabel('Samples'); ylabel('Volt');

PlotCalcaneus = str2double(Calcaneus); 
figure(4)
plot(PlotCalcaneus);
title('Calcaneus'); xlabel('Samples'); ylabel('Volt');

This is my Arduino code:

void setup() 
{
  // Start serial at 9600 baud
  Serial.begin(9600); 
}

    void loop() 
{
  // Read the input on analog pin 0:
  int sensorValue = analogRead(A0);
  int sensorValue2 = analogRead(A1);
  int sensorValue3 = analogRead(A2);
  int sensorValue4 = analogRead(A3);
  
  // Convert the analog reading (which goes from 0 - 1023) to a voltage (0 - 5V):
  float voltage =  (sensorValue * (3.3 / 1023.0) * 33.33); // *33.33 er for at omdanne til N, sensoren kan give 1023 outputs, og de 0-3.3 v inddeles her. Hvis 110N er max og 3.3 v er max, diveres de for at finde omformningskonstanten. 
  float voltage2 = (sensorValue2 * (3.3 / 1023.0) * 33.33);
  float voltage3 = (sensorValue3 * (3.3 / 1023.0) * 33.33);
  float voltage4 = (sensorValue4 * (3.3 / 1023.0) * 33.33);
  
  // Print out the value you read:
 

{
  
  Serial.print(" Heel  ");
  Serial.print(voltage,4);
  Serial.print(" Metatars ");
  Serial.print(voltage2,4);
  Serial.print(" Svang ");
  Serial.print(voltage3,4);
  Serial.print(" Calcanus ");
  Serial.print(voltage4,4);
  
  
  Serial.println();
}
 
    
  // Wait 100 milliseconds
  delay(100);
}

I hope you can help me - Kasper