Error using matlab.ui.​control.UI​Control/ge​t Invalid or deleted object inside a while loop

I click on the plot data in an axes window all goes fine, except when i finish/end the gui this error occurs.

Error using matlab.ui.control.UIControl/get
Invalid or deleted object.

Error in BSAKit>pbtECG_Callback (line 207)
    while get(hObject,'Value')

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

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

Error in matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)BSAKit('pbtECG_Callback',hObject,eventdata,guidata(hObject))
 
Error while evaluating DestroyedObject Callback.

Code:

function pbtECG_Callback(hObject, eventdata, handles)
% hObject    handle to pbtECG (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
    clc;
    global ecgdata;
    warning off
    yMax  = 1.5;                           %y Maximum Value
    yMin  = -0.5;                      %y minimum Value
    plotGrid = 'on';                 % 'off' to turn off grid
    min = 0;                         % set x-min
    max = 5;                        % set x-max
    delay = .001;                     % make sure sample faster than resolution 
    t = 0;
    e1 = 0;
    e2 = 0;
    e3 = 0;
    plotTitle = 'ECG plot';  % plot title
    xLabel = 'Time (s)';     % x-axis label
    yLabel = 'ECG (V)';      % y-axis label
    legend1 = 'Lead 1';
    legend2 = 'Lead 2';
    legend3 = 'Lead 3';

    switch get(hObject,'Value')
        case 0
            set(hObject,'String','Start')
            fprintf(handles.serConn, 'e');
        case 1
            set(hObject,'String','Stop')
            set(handles.serConn, 'TImeout',2);

            axes(handles.axeChannel1);
            cla;
            legend(legend1);
            axis([min max yMin yMax]);
            axis 'auto y'  % moi them vao
            grid(plotGrid);
            hold on
            li1=line(NaN,NaN);
            
            axes(handles.axeChannel2);
            cla;
            legend(legend2);
            axis([min max yMin yMax]);
            axis 'auto y'
            grid(plotGrid);
            hold on
            li2=line(NaN,NaN);
            
            axes(handles.axeChannel3);
            cla;
            legend(legend3);
            axis([min max yMin yMax]);
            axis 'auto y'
            grid(plotGrid);
            hold on
            li3=line(NaN,NaN);
            
            fprintf(handles.serConn, 'E');
            ei=0;
            ecgdata=[0 0 0 0 0 0 0 0 0 0 0 0; 0 0 0 0 0 0 0 0 0 0 0 0];
    end
    tic
    time1=0;
    time2=0;
    ecg1=[0];
    ecg2=[0];
    ecg3=[0];
    x=[0];
    while get(hObject,'Value')    
        data = fscanf(handles.serConn, '%s');
        %count=100;
        %maxloop=2;
        %while((count>50)&&(maxloop>0))
        %    [data,count] = fscanf(handles.serConn, '%s');
        %    maxloop=maxloop-1;
        %end
        sa = str2num(data);
        if(size(sa,2)>11)
            ei=ei+1;
            %ecgdata(ei,:)=sa;
            ecgdata(ei,:)=[sa(1) 0.04185.*sa(2:9)-685.71 sa(10:12)];
            if(get(handles.chkPlotECG,'Value'))
                e1=sa(2);
                e1=0.04185*e1-685.71;%1000*((e1/32768)-1/2)*4.8/3.5;
                e2=sa(3);
                e2=0.04185*e2-685.71;%1000*((e2/32768)-1/2)*2*2.4/3.5;
                e3=e1-e2;
                temp=sa(1)/1000;
                    x=[x temp];
                    ecg1 = [ecg1 e1];
                    ecg2 = [ecg2 e2];
                    ecg3 = [ecg3 e3];
                if(temp-time1>=0.1)
                    time1=time2;
                    time2=temp;
                    set(li1,'XData',[get(li1,'XData') x], 'YData',[get(li1,'YData') ecg1]);
                    set(li2,'XData',[get(li2,'XData') x], 'YData',[get(li2,'YData') ecg2]);
                    set(li3,'XData',[get(li3,'XData') x], 'YData',[get(li3,'YData') ecg3]);
                    x=[];
                    ecg1=[];
                    ecg2=[];
                    ecg3=[];
                    if(time2>max)
                        set(handles.axeChannel1,'XLim',[(time2)-max time2]);
                        set(handles.axeChannel2,'XLim',[(time2)-max time2]);
                        set(handles.axeChannel3,'XLim',[(time2)-max time2]);
                    end
                end
            end
        end
        t=t+1;
        pause(delay);
    end

[Rik]

'when you're finished'

Did you close the figure window? How did you make sure the while loop exists properly before the object this callback refers to is destroyed?

[Walter Roberson]

Exactly. When you close the figure window, the object stops existing. You should

while isvalid(hObject) && get(hObject,'Value')