How to create a multi thread gui

Hello how can i plot data real time in a gui?

The code below keeps blocking.I want when i press the close_port_btn the reading to stop. Since i have seen there is no function to get the serial status of the port i created that flag. This flag is intended to stop the reading. Somehow it seems the code won't exit that part of code. Do i need to do multithreading? And if so how can i achieve that?

function read_btn_Callback(hObject, eventdata,handles)
  % hObject    handle to read_btn (see GCBO)
  % eventdata  reserved - to be defined in a future version of MATLAB
  % handles    structure with handles and user data (see GUIDATA)
  global port;
  fopen(port);

    handles.flag=1;
    N=100;
    y=zeros(N,1);
    t=linspace(0,N,1);
    while (handles.flag~=0)
        y(1:end-1)=y(2:end);
       x=fscanf(port,'%d')/100
        plot(y,'LineWidth',2);
         grid on;
         axis([0 100 0 50])

    end
    guidata(hObject,handles);

function close_port_btn_Callback(hObject, eventdata, handles)
% hObject    handle to close_port_btn (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
global port;
fclose(port);
handles.flag=0;
guidata(hObject,handles);

Answer 1

[Walter Roberson]

function read_btn_Callback(hObject, eventdata,handles)
    % hObject    handle to read_btn (see GCBO)
    % eventdata  reserved - to be defined in a future version of MATLAB
    % handles    structure with handles and user data (see GUIDATA)
    global port;
    fopen(port);

      handles.flag=1;
      guidata(hObject, handles);

      N=100;
      y=zeros(N,1);
      t=linspace(0,N,1);

      while true

        drawnow();
        handles = guidata(hObject);
        if handles.flag == 0
          break;
        end
        y(1:end-1)=y(2:end);
        x=fscanf(port,'%d')/100
        plot(y,'LineWidth',2);
        grid on;
        axis([0 100 0 50])

      end

      fclose(port);

function close_port_btn_Callback(hObject, eventdata, handles)
% hObject    handle to close_port_btn (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
handles.flag=0;
guidata(hObject,handles);

[Adrian Bercovici]

Thank you for your answer.Indeed it stops blocking if you press close port but it won't plot.

[Walter Roberson]

You initialize your y to N zeros's and in your loop you shrink y by one element each pass through the loop. An all-zero line could easily be mistaken as not being there.

You read data into x in your loop but you do not store or plot that x.

[Adrian Bercovici]

 I added a pause and it seems it did the trick however i get this error after closing the port.

I want the reading to be dependent on the status of the port ,handles.port_stt.

*

Error using serial/fscanf (line 154)
  Unsuccessful read: OBJ must be connected to the hardware with FOPEN.*

function open_port_btn_Callback(hObject, eventdata, handles)

    global myport;
    %----------------------Port opening-----------------------%
    %
    handles=guidata(hObject);
    if(~strcmp(handles.port_stt,'opened'))
    fopen(myport);
    handles.port_stt='opened';
    guidata(hObject,handles);
    end

    % --- Executes on button press in close_port_btn.
    function close_port_btn_Callback(hObject, eventdata, handles)
    global myport;

    %----------------------Port closing-----------------------%
    handles=guidata(hObject);
    if(~strcmp(handles.port_stt,'closed'))
    fclose(myport);
    handles.port_stt='closed';
    guidata(hObject,handles);
    end

    % --- Executes on button press in read_btn.
    function read_btn_Callback(hObject, eventdata, handles)
    global myport;
    handles=guidata(hObject);

        while(strcmp(handles.port_stt,'opened'))
            handles=guidata(hObject);
            x=fscanf(myport,'%f')/100
            pause(0.0001);
        end