How can I update Text box dynamically(in regular intervals) in Matlab GUI?

Below is the callback function for the pushbutton run in the GUI: I want to run a while loop which continuously updates the value in the edit text box of the GUI with value from the simulink model but as soon as I press the RUN button in the GUI, it goes into infinite while loop and the simulation does not run.

function pushbutton_run_Callback(hObject, eventdata, handles)

handles=guidata(hObject);

flag=get(hObject,'string');

if strcmp(flag,'RUN')==1

set_param(handles.modelname,'SimulationCommand','Start');

set(hObject,'string','STOP');

while(strcmp(get(handles.pushbutton_run,'string'),'STOP'))

      %some code for updating text box

end

else

set_param(handles.modelname,'SimulationCommand','Stop');

set(hObject,'string','RUN');

end

guidata(hObject,handles);