程序运行时断开USB设备

Question

在程序运行时手动断开连接后尝试重新连接到USB设备，基本上启动程序时出现“点击”事件，现在我要问的是，是否有一些代码检查断开连接后是否重新连接。

Try
'code executing here, then the device is disconnected while this code is running
 If oflag = False Then 'oflag is false by default
     SerialPort1.PortName = ("Com" & COMnum)     'Assigns the serial port name
     SerialPort1.Open()
 End If
'extra code after this
Catch ex As IOException
     MsgBox("BLAH")
     oflag = True 'this used
     Exit Sub
End Try