In callback for the stop button, set app.stopFlag = true;
Within the plotting function check the property
Read this as well.
You can use a callback function to change the value of a flag that is checked repeatedly within the plotting commands.
Define the flag as a public property of the app (see instructions) so the external function has access to the flag.
The app's startup function would set the flag to false: app.stopFlag = false;
The callback function would merely set the flag to true: app.stopFlag = true;
Within the external (or internal) function, you can use the condition,
Note that if you return before the function is complete, you'll need to assign default output values and you may need to add return commands to any other invoking functions.
Then, the flag should be reset: app.stopFlag=false.