MATLAB串口开关问题

xiannvjiejie

先描述下问题现象：
        正常打开关闭一次串口后，再次打开串口提示：
       打开失败: Cannot connect to the COM31port. Possible reasons are another application is connected to the port or the port does not exist. 出错 MSerialV1>pbOpenAndClose_Callback(line 122)    fopen(s);

确认该串口没有在其它程序中使用！
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以下是程序代码

set(handles.pmComPort,'String',seriallist);
indexCom = get(handles.pmComPort,'Value');
strCom = get(handles.pmComPort,'String');
if indexCom > 1
    comPort = strCom(indexCom);
else
" j3 Z9 \. Q0 i- o& C$ l    comPort = strCom;   
end
s = serial(comPort);
8 A! g% R' a2 e$ Q4 ?' ]/ v; zif handles.pbOpenAndClose.String == "打开"
    handles.pbOpenAndClose.String = "关闭";
    handles.pbOpenAndClose.BackgroundColor = 'g';
    fopen(s);   
7 }/ b+ Z3 p1 w+ b. R) _5 melse
    handles.pbOpenAndClose.String = "打开";
    handles.pbOpenAndClose.BackgroundColor = 'r';
6 d9 q5 x0 |& v& t- f    fclose(s);
( q2 o! P" {# \' c    delete(s);
, X1 X1 s/ f5 e& ^: ~) Y    clear s;
" [5 I* A  O0 }6 R% x; V6 oend
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finishedabc

试试过程中用指令能否正常退出串口，关闭串口