MATLAB App Designer: Error while evaluating TimerFcn for timer 'timer-5' Undefined function 'write' for input arguments of type 'string'.

Question

Yu Zhu 2022-9-20

0
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https://ww2.mathworks.cn/matlabcentral/answers/1808415-matlab-app-designer-error-while-evaluating-timerfcn-for-timer-timer-5-undefined-function-write

回答： Shreyansh Mehra 2022-9-23

Hi, i am trying to use a timer to send data through serial port to arduino at a fixed rate. However, the error is like this: Error while evaluating TimerFcn for timer 'timer-5' Undefined function 'write' for input arguments of type 'string'.

This is the code related to the timer:

function startupFcn(app)

app.mytimer = timer('Period',0.2,'ExecutionMode','fixedRate');

app.mytimer.TimerFcn = @app.TimerCallback; % Your Timer Callback

end

This is the timer call back function:

function timertt = TimerCallback(app, ~, ~)

% Timer callback

app.sendData(app.motor_qc);

end

function sendData(app,tosend)

tosend = string(tosend);

write(app.arduino,tosend,"string");

end

I'm sure "write" for "string" can work ouside the timer. I used a button to trigger the sendData function, and it works well. But if it is inside the timer, it doesn't work. Is there any solution for this?