MATLAB GUI: Axes do not retain modifications when using the plot function

Hi, everyone I'm working on a Matlab GUI, I acquire samples over COM, there is a callback every N samples, then I plot them on GUI. The problem is as follow: in GUI Opening Function I make some axes initializations (axes tick, axes limits, axes labels...) and it's all correct when the GUI is opened but as soon as data are plotted the axes loose the lables and part of the YTick personalization. I've attached the code to discuss with you searching for my possible faults.

%Axes initialization
handles.axes1.YTickMode = 'manual';
handles.axes1.XTickMode = 'manual';
handles.axes1.YLimMode = 'manual';
handles.axes1.XLimMode = 'manual';
ytickformat(handles.axes1,'%.2f');
handles.axes1.XLabel.String = 'Samples';
handles.axes1.YLabel.String = 'Voltage';
handles.axes1.YLim = [0 3.0];
handles.axes1.XLim = [0 1000];
handles.axes1.YTick = [0 0.25 0.5 0.75 1.0 1.25 1.5 1.75 2.0 2.25 2.5 2.75 3.0];
handles.axes1.XTick = [0 250 500 750 1000];

    %Serial Callback
    function serialcallback(hObject)
          handles = guidata(hObject);                      
          buffer = fread(handles.serConn, 3000, 'uint16');
          j=0;
          for k = 1:3:3000
              j = j+1;
              handles.Volt(j) = double(buffer(k))*(3.0/4095.0);
              if k > 1
                  handles.Temp(j-1) = buffer (k-2);
                  handles.Curr(j-1) = buffer (k-1);
              end
          end
          plot(handles.axes1,handles.Volt);
          guidata(hObject,handles);

Thank you to everyone for the support.

[Jan]

Please post the relevant part of the code only. It is not efficient to let the readers search for the lines you are talking of. Thanks.

[Dario Laezza]

Thanks for the tip, I've modified the question.

Answer 1

[Jan]

It is the documented behavior of the high-level graphics functions like plot to adjust the properties of the axes object automatically. To avoid this, you can use low-level functions like line, or fix the axes' properties by:

axes('NextPlot', 'add')
% Equivalent:
% hold('on');

I assume in your case:

handles.axes1.NextPlot = 'add';

This has the effect, that formerly existing line objects are not deleted by plot automatically anymore, such that you have to do this explicitly on demand:

delete(handles.axes1.Children)

By the way: Better omit the loop and make the code nicer in the serialcallback:

handles = guidata(hObject);                      
buffer  = fread(handles.serConn, 3000, 'uint16');
handles.Volt = double(buffer(1:3:end) * (3.0/4095.0);
handles.Temp = buffer(2:3:end);
handles.Curr = buffer(3:3:end);

[Dario Laezza]

Thank you Jan, I understood that the plot function was the 'problem', I'm grateful for your tips. Thank you also for loop's tips, I'm new in Matlab so I use to have a "C" approach.

[Jan]

The "vectorized" approach without the loop is faster and offers less chances for a typo during programming.