how to use handles to connect app designer and simulink with each other

This is the first time using the option to ask the community because i am stuck for two days now. I had to write a rather complex program in stateflow (stateflow runs inside of simulink) and did so successfully. Now i have to create a user interface for easier usage. I have no experience in doing so and after some unsuccsessful tries in GUIDE i switched to app designer. In the startup funtion off the app i simulate the Simulink model "Simulation".

              sim('Simulation');

later by changing a value in a constant block i started the actual simulation:

              set_param([bdroot '/start simulation'], 'Value', 'true');

1. However after closing the app the Value stays true. Is there any way of only changing the value temporarily without using a reset button inside of the app?

2. To connect the Simulink model with the GUI i have read in multiple threads, that i have to use handles. ( App Designer to control a Simulink Model and read back model data ) However I don't know where to put the code for the handle (do I have to put both into the startup function of the app?) At the moment i try to access the app from a matlab_function inside of simulink (Gewebeinfiltrationsautomat_EXE is the name of the mlapp-file)

function fcn(process_timer, actual_sample_size, finished,)
app_handle = Gewebeinfiltrationsautomat_EXE;
app_handle.lbl_timer.text = num2str(process_timer);

Do i have to create the handle in the startup function of the app? If yes, can I then simply access the handle from any matlab function without problem?

Thank you for your help.

[Bartha Balazs]

Hi, did you found any solution to your problem ? I'm struggling with a similar issue so if you have any solution peas let me know :)

Answer 1

[Philipp Küsters]

I have. You can access public app designer functions with coder.extrinsic. You first have to create the functions in App Designer. Then you create a handle in Simulink/Stateflow. My initialise block looks like this:

initialise
% initialise app and import the apps interface
en: coder.extrinsic('gia_app', 'update_clock', 'update_sample1', 'update_sample2', 'update_position1', 'update_position2' ,'update_display', 'update_finished'); %'update_temp9', 'update_temp10', 'update_temp11')
 app = gia_app();

(This is written in a stateflow chart. I do not know how to implement it in Simulink without the use of Stateflow.)

-"app" is the handle i create -"gia_app" is the name of my app designer file -everything except "gia_app" behind "coder.extrinsic" is a public function in the app designer file

The functions can now be called in Stateflow. example:

update_display(app, message)

You can even pass variables, like in this case message. The public function "update_display" has exactly one input argument. This is the app designer code of the function:

          function results = update_display(app, input)

%             0 = start
%             1 = change pos of sample1
%             2 = change pos of sample2
%             3 = spectate sample1
%             4 = spectate sample2
%             5 = mix
%             6 = waiting
% 
            if input == 0
                new_line = 'Prozessstart';

...

Important Note: If you want to pass variables from App Designer to the running Simulink-Simulation, you will probably save them in the Matlab base-workspace. Simulink does not update the Variables automatically, while the simulation is running!!! Whenever you change a variable in App Designer or generally somewhere outside of the running Simulink-Simulation, you have to pause, update and continue the simulation. (This will not notice the pausing, this is all done in very short time). example:

              set_param('gia_sim' ,'SimulationCommand','pause');    % pause simulation, so variables can be read
              assignin('base', 'pres11', value);                    
              set_param('gia_sim','SimulationCommand','update');    % update app with new variable
              set_param('gia_sim','SimulationCommand','continue');

Hope I could help you. If you have more questions I would be happy to help. Im pretty busy myself right now though, so it could take some time.

[Eric Hannouz]

Hello Philipp, What Type did you use for the StateFlow Local variable "app" ? If you use an Expression like "gia_app", don't you have a compilation error of the kind "Expression 'gia_app' for type of data 'app' did not evaluate to a valid type" ?

[Philipp Küsters]

Hi Eric, I used a local Variable of size -1 with inherited complexity and no start value. Make sure your files are in the same folder. I don't get any error messages. Here's a snap of my chart's top layer.

Good luck with your project.