Stop a Execute Callback Function - MATLAB - function

Question

i check every two seconds if a EXE is running. If its not running then check in a .mat file a value. If value is 1 then the program should stop(t). At moment the stop(t) isnt working or if i leave it out then i have infinite loop.
t=timer;
t.period=2;
t.TasksToExecute=inf;
t.ExecutionMode='fixedRate';
t.TimerFcn=#check_exe;
start(t)
function check_exe(mTimer,~)
%check if EXE is already running
[~,b]=system('tasklist');
IsRunning=contains(b,'Digitale_Ablegeschablone');
if IsRunning(1)
fprintf('Digitale_Ablegeschablone ist bereits geöffnet!\n');
else
load('Parameter.mat', 'Speicherstatus')
load('Parameter.mat', 'Block_beendet')
load('Parameter.mat', 'Save_Session')
if Save_Session==1
fprintf('Sitzung ist gespeichert. Digitale Ablegeschablone wird nicht geöffnet\n');
stop(t) %stop
elseif Block_beendet==1
fprintf('Sitzung ist beendet. Digitale Ablegeschablone wird nicht geöffnet\n');
stop(t) %stop
else
%start again (if its crashed)
system('C:\Users\christian\Desktop\TEST\EXE\Digitale_Ablegeschablone.exe &')
end
end
end

Answer 1

You are calling stop(t) inside a function which doesn't "know" what t is - it is not defined anywhere in the scope of that function, hence the error message you get
Unrecognized function or variable 't'.
The first input to the callback function check_exe, which you're not using at all currently, is actually the timer object. However, you've called it mTimer instead of t. You need to either use stop(mTimer) or change the input name to t. A simpler complete example which just checks if some test file exists can be used to test this:
function check(t,~)
if exist( 'C:\Users\wfeavyou\Desktop\test.txt', 'file' )
fprintf( 'Stopping at time=%dsec!\n', (t.TasksExecuted-1)*t.Period );
stop(t) %stop
else
fprintf( 'Check failed, continuing at time=%dsec!\n', (t.TasksExecuted-1)*t.Period );
end
end
This produces the following output where I manually made the test.txt file after 6 seconds. I can't test it because your example isn't stand-alone, but it should work in the same way just by changing the first input name to t
Check failed, continuing at time=0sec!
Check failed, continuing at time=2sec!
Check failed, continuing at time=4sec!
Check failed, continuing at time=6sec!
Stopping at time=8sec!