Hi Murali,
In the context of your AppDesigner class, the execAlive method is defined with the class instance (app) as its third argument. However, when setting up the timer callback, MATLAB expects the first input to the callback function to be the source of the event (in this case, the timer object t) and the second input to be the event data, which is usually empty ([]) for timer callbacks. Your execAlive method is defined to ignore the first two arguments and expects the third argument to be the app instance itself, which is correct for how you're intending to use it.
To resolve this issue, you should use the method within the context of the class instance (app). Here's how you can adjust your timer callback registration to correctly reference the execAlive method within the class:
% Button pushed function: STARTButton
function STARTButtonPushed(app, event)
app.t = timer('Period', 2 , 'ExecutionMode', 'fixedRate');
% Adjust the TimerFcn to use a function handle that calls execAlive on app
app.t.TimerFcn = @(src, event)execAlive(app, src, event); % Correctly reference execAlive
start(app.t); % Don't forget to start the timer
end
