It is possible to act on Simulink models from App Designer in a similar fashion to GUIDE.
Please find attached a simple App 'MW_app' where it is possible to open, simulate, close and increase the value of the gain in the Simulink model 'vdp'.
The App has been developed in the following way:
1. Open App Designer:
>> appdesigner
2. Drag and rename four push buttons.
3. Right-click on each respective push button > Callbacks > Add pushed function callback > Write your own code
4. Save the app
You can then use the App to act on the Simulink model 'vdp'. If you wish to modify the App or see its Code View, please type the following line at the MATLAB Command Window:
>> appdesigner MW_app
To create a more complex app that takes in data from a running simulation, see the following MATLAB Answers Post:
