Index exceeds matrix dimensions plotting in GUI

Hello this callback function in the GUI is made to plot continously the values of 3 temperature sensors from the acquisition board. The acquisition board sends a large string containing data every 2 seconds.The string has comma's as parameter delimiters.I use strsplit similar to strtok to get "words" from the string ;i am interested in the words 1,4,7 which represent the temperature values.After i store them itransform them in double .After that i plot them and write the data in a file.I don't know why but i keep getting this timeout warning and this error:

**Warning: Unsuccessful read: A timeout occurred before the Terminator was reached. Index exceeds matrix dimensions.

Error in gui_3>read_btn_Callback (line 144) s2=(str2double(string(4)))/100;*

Error in gui_mainfcn (line 95) feval(varargin{:});

Error in gui_3 (line 42) gui_mainfcn(gui_State, varargin{:});

Error in @(hObject,eventdata)gui_3('read_btn_Callback',hObject,eventdata,guidata(hObject))*

function read_btn_Callback(hObject, eventdata, handles)
global myport;
handles=guidata(hObject);
handles.y0=zeros(handles.samples,1);
handles.y1=zeros(handles.samples,1);
handles.y2=zeros(handles.samples,1);
guidata(hObject,handles);
i=0;
a=fopen('Data.txt','wt');

      while(strcmp(handles.port_stt,'opened'))
          handles=guidata(hObject);
          drawnow
           handles.y0(1:end-1)=handles.y0(2:end,1);
          handles.y1(1:end-1)=handles.y1(2:end,1);
          handles.y2(1:end-1)=handles.y2(2:end,1);
       if(strcmp(handles.port_stt,'opened'));
          data_row=fscanf(myport,'%s');
          string=strsplit(data_row,',');
          guidata(hObject,handles);
          s1=str2double(string(1));
          s2=str2double(string(4));
          s3=str2double(string(7));

          handles.y0(end)=s1;
          handles.y1(end)=s2;
          handles.y2(end)=s3;
          fprintf(a,strcat(data_row,'\n'));

       end
          plot(handles.axes1,0:handles.samples-1,handles.y0,'--','LineWidth',2,'Color','g');
          grid(handles.axes1, 'on')
          ylim(handles.axes1,[0 100]);
          plot(handles.axes2,0:handles.samples-1,handles.y1,'--','LineWidth',2,'Color','g');
          grid(handles.axes2, 'on')
          ylim(handles.axes2,[0 100]);
          plot(handles.axes3,0:handles.samples-1,handles.y1,'--','LineWidth',2,'Color','g');
          grid(handles.axes3, 'on')
          ylim(handles.axes3,[0 100]);
          guidata(hObject,handles);
          pause(0.0001);

      end
     fclose(a);