Problem with Callback Function / BytesAvailableFcn on GUI

i work since 3 days only on one thing ; to be able to receive continuously bytes from device (Arduino) on GUI programme but unfortunately i have not done. The Problem is that BytesAvailableFcn cannot be called.

function togglebutton1_Callback(hObject, eventdata, handles)

stat = get(hObject,'Value'); %returns toggle state of togglebutton1

if (stat == 1)  

      if ~isfield(handles, 'Ser')

      set(hObject, 'String','Connected');
      handles.Ser = serial('COM11','BaudRate', 9600); 
      handles.Ser.BytesAvailableFcnMode = 'Terminator';
      set (handles.Ser,'RequestToSend','off');
      set (handles.Ser,'Terminator','CR');
      handles.Ser.BytesAvailableFcn = {@instrcallback,handles}; % Here the Problem!
      fopen(handles.Ser) ;

      end

elseif (stat == 0) 

      if isfield(handles, 'Ser')
        fclose (handles.Ser);
        handles = rmfield(handles, 'Ser');   
      end

end 
guidata(hObject, handles)  

function instrcallback(obj, eventdata, handles)
set(findobj('Tag','text2'),'String','Bytes Received!') ; % Test if that function works

[Walter Roberson]

You did not say what difficulty you are encountering. Is the callback not being invoked? Have you tried

get(handles.Ser,'BytesAvailableFcn')

to be sure that it has been set to what you want?

[Yassin Kim]

Yes that's the Problem, i tried already :

get(handles.Ser,'BytesAvailableFcn')

and i got 0 I can receive Data with command

fscanf(handles.Ser)

in a loop while but i would like to use a callback function.

[Yassin Kim]

But if i use

Ser = serial('COM11','BaudRate', 9600); 
Ser.BytesAvailableFcnMode = 'terminator';
Ser.BytesAvailableFcn = @instrcallback;
Ser.OutputEmptyFcn = @instrcallback; 
set (Ser,'RequestToSend','off')
set (Ser,'Terminator','CR');  
fopen(Ser) ;

in Command Window, i get

BytesAvailable event occurred at 18:38:36 for the object: Serial-COM11.

The Probleme is only with function instrcallback, it works when i delete it

%function instrcallback(obj, eventdata, handles)
%set(findobj('Tag','text2'),'String','Bytes Received!') ;

Answer 1

[Harsha Medikonda]

'instrcallback' accepts two parameters. Please refer to the following documentation link

instrcallback

Also,please refer to the following link for the usage of bytesavailablefcn

bytesavailablefcn

[Walter Roberson]

True, however it is only an error to specify more dummy parameters than actual arguments if one of the missing arguments is actually used.