What is the correct way to close a serialport connection in App Designer?

As per the the serialport documentation, the way to create and delete a serial connection should be

s = serialport(device,baudrate);
clear s;

However, in app designer, I want multiple functions to be able to read/write to the port, so I have made s a property of the app. You can't clear an app property thought. So what is the correct way free app.s so it can be reconnected to the same device later?

Failing to clear s gives the usual error of "Unable to connect". Setting app.s to some other value, and then creating a new serialport object doesn't close the old connection (i suppose it overwrites the location of the serialport object).

Answer 1

[Jingyi Zhou]

I find a solution for this question.

First, I add a public property for this app. It is called Serial_Port, used to save the serialport objet.

properties (Access = public)
        Serial_Port % Description
end

then, when I want to open a serial

app.Serial_Port = serialport(app.DropDown_SerialPort.Value,str2double(app.DropDown_Baudrate.Value));

when I want to close this serialport,

app.Serial_Port = [];

And because this property is public, this open and close command don't have to be in the same function.

Hope can help you~

[Patrick Stoll]

This worked for me, Thank you

Answer 2

[Dominik Mair]

Hi!

I used a "dirty" workaround with the old guis. Maybe something similar works with apps:

In an old project i used following containing my serialport object:

handles.ACTIVECOMPORT

If i want to reset it i used:

temp=handles.ACTIVECOMPORT;

handles.ACTIVECOMPORT=[];

delete(temp)

Answer 3

[Harsha Priya Daggubati]

Hi,

I guess you can set app.s to an empty value, after all the intended work is done.

Link to a similar question:

https://in.mathworks.com/matlabcentral/answers/322585-clearing-variables-from-memory-matlab-app-designer

Hope this helps!

[Nolan King]

Unfortunatly that doesn't close the serial connection, which is the point of clearing the variable.