程序非法中止后,COM口怎么强行关闭。

Option Explicit

    Dim a As Integer

Private Sub Command1_Click()

    On Error GoTo uerror

    For a = 1 To 16

        MSComm1.CommPort = a

        MSComm1.PortOpen = True

        If MSComm1.PortOpen = True Then

            Print "可用Com号= "; a

            MSComm1.PortOpen = False

        Else

        End If

    Next

    Exit Sub

uerror:

    Print "出错或占用Com号= "; a

    Resume Next

End Sub

Private Sub Form_Load()

    On Error GoTo userr

    MSComm1.PortOpen = True

    'Print MSComm1.PortOpen

    Exit Sub

userr:

    If MSComm1.PortOpen = True Then

        MSComm1.PortOpen = False

    End If

    'Print MSComm1.PortOpen

    Resume

End Sub