How do I close the port Arduino is connected to?

I have developed a GUI which uses the Arduino support package. Every time I close and rerun the program an error pops up saying the port is already being used by MATLAB. I clear all the variables and can rerun the program without any issues. I wanted to know if there was a way to close the connection with the arduino when the figure is closed.

I already tried to delete the arduino object but that did not work. I also tried to clear the object which also oddly did not work. Can someone help?

[Adithya Vivek]

Dear Mathews, I apologize for not being able to answer your question, but could you please help with a similar problem I have? I am trying to create a way to autodetect the com port the arduino is connected to such that I can create an application usable on any Windows computer. I created a link for this question here: https://www.mathworks.com/matlabcentral/answers/349958-auto-detection-of-the-com-port-that-arduino-is-connected-to-then-defined-as-an-argument-that-can-be

I would be infinitely grateful!

[PAUL ANGARITA]

I will give my contribution. Sorry for late reply. I recommend using the Command

.... clear... .

Remember it cleans all Variables in WORKSPACE. If you need to delete only the object ...a = arduino().. so only delete ...a

Remember to close or delete all objects regarding arduino stuff, firstly.

Answer 1

[Mathews John]

I think I figured it out.

a = arduino(); %Creates an arduino object and connects to the hardware.
% Do stuff while open
fclose( serial(a.Port) ); %Create a serial object with the port Arduino is connected to it and close it
clear a; %Remove the variable

Don't know if there's a better way

[Image Analyst]

Not that I know of. It's only a line of code so I don't know how it could be simpler or better. glad my suggestion of fclose() worked for you.

[Bill Silk]

Worked for me -thank you.

Answer 2

[Azrg]

Whenever I get the message that a Arduino is already used when it is not, I use these two functions:

fclose(instrfindall);
delete(instrfindall);

Works for me :) hope it helps someone else who has this issue

Answer 3

[Image Analyst]

Perhaps call fclose():

s = serial('COM1');
fopen(s)
fprintf(s, '*IDN?')
idn = fscanf(s);
fclose(s)

[Mathews John]

Sorry for the late reply. I just tried this and it did not work.