How to use GUI handles in external function?

I have a task, where a server reads incoming messages and works with them to eventually display them on an axis in a GUI. For this task, BytesAvailableFcn is perfect, but I have some problems implementing it. I am able to pass the handles structure to it and to use the variables inside, but I am not able to update it in the end. Parts of my code, that are relevant:

%Configuration of the port

handles.TCPL = tcpip('0.0.0.0', 31010, 'NetworkRole', 'server');

handles.TCPL.BytesAvailableFcnCount = 23;

handles.TCPL.BytesAvailableFcnMode = 'byte';

handles.TCPL.BytesAvailableFcn = {@nuskaitymas,handles};

%

%

%

%

%The callback function-----------------------------------------------------------

function nuskaitymas(hObject,eventdata,handles)

%Takes the handles structure, uses variables inside it

.

.

.

%This part of the code is not relevant

.

.

.  

%Update handles structure

guidata(hObject, handles);

end

----------------------------------------------------------------------------------

What happens is when I call "guidata", the hObject gets marked with an error. Any ideas?

Also, what I have tried is instead of doing the calculations inside the callback, is to change a global variable inside the callback to stop a while loop inside the main function of the GUI, but what happens is that the program waits for the while loop to stop, before calling the BytesAvailableFcn.

[Geoff Hayes]

Tautvydas - you say that What happens is when I call "guidata", the hObject gets marked with an error. What is the error? Please copy and paste the full error message to your question.

[Tautvydas Belgeras]

This is the error that I get

 Error using guidata (line 87)
 H must be the handle to a figure or figure descendent.

 Error in nuskaitymas (line 80)
    guidata(hObject, handles);

 Error in instrcb (line 36)
        feval(val{1}, obj, eventStruct, val{2:end});

[Tautvydas Belgeras]

Should I note that the callback function "nuskaitymas" is on a separate m file?

Answer 1

[Greg]

function nuskaitymas(hObject,eventdata,handles)

Is the callback for your tcpip object. The hObject argument is therefore the tcpip object itself (not a graphics component of your GUI) which is not compatible with guidata.

Change the last line to:

guidata(handles.figMyGUI,handles); % Change "figMyGUI" to any valid graphics object tag in handles