How do I write from a GUI button in a simulink parameter ?

Hello I'm writing a GUI (without GUIDE) in order to control inputs in a simulink model (for example a command controlled by the user in the GUI, this command being an input in simulink model). Here is the code of the GUI:

function varargout = OHP_Fuel_Panel(varargin)
% MYGUI Brief description of GUI.

% Creation of matlab figure
  ohp_h = figure('MenuBar','none','Name','OHP - Fuel Control Panel',...
             'NumberTitle','off','Position',[360,500,450,285]);

%  Construct the components
L_BP1_h = uicontrol(ohp_h,'Style','togglebutton','String','OFF','Value',0,...
    'Position',[30 20 100 30],'callback',@change_label);

%  Callbacks for MYGUI
    function change_label(L_BP1_h,eventData)

          pump_status = get(L_BP1_h,'Value');

          if (pump_status==1)
            set(L_BP1_h,'String','ON');
          else
            set(L_BP1_h,'String','OFF');
          end

          set_param('VSO/Left BP1 command','Value', pump_status);

      end

end

The simulink model is made of a block constant 'Left BP1 command' for which the value is set to "pump_status" and this block is simpky sent to an output port. In the matlab command window, I launch the GUI by its file name, then I run the simulink simulation. But I got the following error message about the GUI:

 ??? Error using ==> OHP_Fuel_Panel>change_label at 40
  Invalid setting in Constant block 'Left BP1 command' for parameter 'Value'.

??? Error while evaluating uicontrol Callback

and this message when I run the simulink model:

Error evaluating parameter 'Value' in 'VSO/Left BP1 command': Undefined function or variable 'pump_status'.

Could you help me to resolve this problem ?

Answer 1

[Sachin Ganjare]

Reason coould be uninitialized variable in workspace, instead of 'set_param' command use 'assignin' in your GUI code.

Hope this helps!!!!!!!!!