How to assign new values to the simulink model blocks while it is executing

function pushbutton1_Callback(hObject,eventdata)
Final_Result=[];
open_system('Desktop\test_Final.slx')
for i=15
set_param('test_Final','StopTime', sprintf('%d',i));
set_param('test_Final','Simulationcommand','start');
options = simset('SrcWorkspace','base');
end

    function pushbutton2_Callback(hObject,eventdata)
    pause(0.44)
    b=5
    assignin('base','b',b)
    set_param('test_Final','Simulationcommand','continue');
    set_param('test_Final','Simulationcommand','update');
  end
How to change the value of b,,,which is constant block im my model,,i just want to change the value of constant block ,,,while simulink model is executing

It looks like you are already changing the value of 'b' in the workspace and running set_param('test_Final','Simulationcommand','update') - does this not work?

Thanks for reply,,,it works