How can I change block parameters in simulink using block path in app designer?

I want to change block parameters (by refrrencing the block's path) in simulink using app designer.

In order to make .exe file I used SimulationInput object as the below code:

simInp = Simulink.SimulationInput('test_model');

I can't use simInp.setBlockParameter because of this error:

and I couldn't use set_param because it dosen't accept SimulationInput object an an input.

Here is the full code:

function startupFcn(app)
            start_simulink;
 end

% Button pushed function: simulateButton
function simulateButtonPushed(app, event)
    try
        simInp = Simulink.SimulationInput('test_model');
        simInp = simInp.setBlockParameter("test_model/Gain",'Gain',num2str(app.kkEditField.Value));
%                 set_param('test_model/Gain','Gain',num2str(app.kkEditField.Value));
        simInp = simulink.compiler.configureForDeployment(simInp);
        simOut = sim(simInp);

        t = simOut.tout;
        y = simOut.yout{1}.Values.Data;
        plot(app.UIAxes,t,y);
    catch ME
        errordlg(ME.message);
    end

end

Would you please help me about the solution?

Answer 1

[Riya]

Hi Sabereh,

I understand that you are getting an error while trying to change a block parameter in Simulink using the “SimulationInput” object in App Designer.

This error happens because you are using “setBlockParameter” along with “simulink.compiler.configureForDeployment”. These two are not compatible — once you configure a simulation for deployment, you are not allowed to modify block parameters directly using “setBlockParameter”.

To resolve this, you can change the block parameter in your model (e.g., “Gain” value) to be a workspace variable, and then use “setVariable” instead of “setBlockParameter” to assign the value.

Here is the corrected code:

function simulateButtonPushed(app, event) 
try 
    simInp = Simulink.SimulationInput('test_model'); 
    simInp = simInp.setVariable('kk', app.kkEditField.Value); % Set gain value using variable 
    simInp = simulink.compiler.configureForDeployment(simInp); % Prepares for EXE 
    
    simOut = sim(simInp); % Run simulation 
    t = simOut.tout; 
    y = simOut.yout{1}.Values.Data; 
    plot(app.UIAxes, t, y); % Plot output 
catch ME 
    errordlg(ME.message); 
end 
end 

To apply this solution, ensure that the “Gain” block in your model has its value set to “kk”(just a variable name) instead of a fixed number. The line setVariable('kk', value) passes this value to the model correctly even when it is compiled into a standalone “.exe”.

For further reference, please see the following documentation:

https://www.mathworks.com/help/simulink/slref/simulink.simulationinput.setvariable.html

[Finlay]

Hi Riya,

I'm looking to do something similar to pass a custom file name to the "record" block from the app so the user can select where to store model outputs. Documentation suggests you can only change the filename by modifying the block parameter directly, but this doesn't seem to be possible in the app designer. Is there any way to achive this?

Thanks,

Finlay