Multiple Com Ports with the same Name

Hello there...I am working on a gui, created with guide (R2016a) which is supposed to open a serial communication port with an µC. All I am trying to implement there I did with several Matlab-Scripts and couple of uicontrols before and it worked quite well.

My problem here is the following: With the first pushbutton, I am trying to open a serial com port.

    s1 = serial('COM3');
    assignin('base','s1',serial('COM3'));
    fopen(s1);

This actually works quite well. Except the output of

    instrfind

right after the first three lines does get me two different indices with the same name. Like this:

    >> instrfind

   Instrument Object Array

   Index:    Type:     Status:   Name:  
   1         serial    open      Serial-COM3
   2         serial    closed    Serial-COM3

My guess this comes due to the two callings of 'serial'. You might be asking WHY i did this: I need to 'fwrite' or 'fread' some bits with another Pushbutton of the gui and I did not found any other way than to

    s1 = evalin('base','s1');
    fwrite(s1,....);

which for I need to store the serial com port "s1" within the workspace. Another Problem is to

    fclose(s1);

because it will not close the remaining open serial com port, but the last one showed with 'instrfind'.

My question here is: Why does Matlab create multiple serials of the same Name and how can I close the serial com port which is open. I could use

      fclose(instrfinde);

but this does not explain, what I am doing wrong. If somebody could point out how to get the serial com port from one function to another, maybe I could ease things up. Thanks in advance!

Answer 1

[Michael schmidt]

I have the exact same problem!