MATLAB: Cannot close connection. MATLAB connection to Due at COM9 exists in your workspace. To create a new connection, clear the existing object.

Question

I cannot close the ports of the arduino after a GUIDE GUI program.

All the commands I have tried at the exit function are:

try
    myArduinoAddonLibrary = getappdata(0,'ARD_AD');
    clear myArduinoAddonLibrary;
    arduinoObj = getappdata(0,'ARD');
    fclose(serial(arduinoObj.Port));
    delete(serial(arduinoObj.Port))
    clear arduinoObj;
catch errorObj
    errordlg(getReport(errorObj,'extended','hyperlinks','off'),'Arduino Error');
end

What would I be doing wrong?

The error that appears when I try to create another Arduino connection in the same port is:

 MATLAB connection to Due at COM9 exists in your workspace. To create a new connection, clear the existing object

For MATLAB 2019a

Answer 1

We solved it using this:

try
    clear
    myArduinoAddonLibrary = getappdata(0,'ARD_AD');
    clear myArduinoAddonLibrary;
    arduinoObj = getappdata(0,'ARD');
    fclose(serial(arduinoObj.Port));
    delete(serial(arduinoObj.Port))
    clear arduinoObj;
catch errorObj
    errordlg(getReport(errorObj,'extended','hyperlinks','off'),'Arduino Error');
end
%Remove appdata from memory
rmappdata(0,'ARD')
rmappdata(0,'ARD_AD')
clear all;

We just added clear at the start made sure the workspace was totally clear at the end.