Using the analog input value from DSP in MATLAB Gui

Hello,

I have used set_param(model,'SimulationCommand','start') to run the simulink model from my gui (my model is in external mode).When I run this simulink model dsp starts working and then the analog input value is saved in workspace.I want use the value in the workspace (which I read from dsp analog input) in MATLAB Gui but ı have an error saying unefined value. The set_param(model,'SimulationCommand','start') works because it does the building in dsp but does not get the workspace values.Can I read the values synchronously? Do you have any suggestion?

Thank you in advance.