怎样让计算机自动的识别插上的USB端口（Com）
想用MSComm控件写一个通信软件，现在有一个不明白的问题，就是我想让软件能自动的识别外接的Com口，以进行选择，请教各位怎么做？ 通信
[解决办法]
不需要 Hook:

'Module: mdlOnDeviceChange
Option Explicit
Private Type DEV_BROADCAST_HDR
    dbch_size           As Long
    dbch_devicetype     As Long
    dbch_reserved       As Long
End Type

Private Type DEV_BROADCAST_VOLUME
    DBCV_Size           As Long
    DBCV_DeviceType     As Long
    DBCV_Reserved       As Long
    DBCV_UnitMask       As Long
    DBCV_Flags          As Integer
End Type

Public Type AUTO_RUN
    flags As String
End Type

Private Declare Function CallWindowProc Lib "user32" _
    Alias "CallWindowProcA" _
   (ByVal lpPrevWndFunc As Long, ByVal hwnd As Long, _
     ByVal Msg As Long, ByVal wParam As Long, _
     ByVal lParam As Long) As Long

Private Declare Function SetWindowLong Lib "user32" _
   Alias "SetWindowLongA" _
  (ByVal hwnd As Long, ByVal nIndex As Long, _
   ByVal wNewWord As Long) As Long

Public Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long

Public Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long

Private hw As Long

Private Const GWL_WNDPROC                As Long = (-4)
Private Const DBT_DEVICEARRIVAL          As Long = 32768
Private Const DBT_DEVICEREMOVECOMPLETE   As Long = 32772
Private Const DBT_DEVTYP_VOLUME          As Long = &H2
Public Const WM_CLOSE                   As Long = &H10
Private Const WM_DEVICECHANGE            As Long = &H219 
 

Public DeviceCallBack           As Long

Public Sub StartUSBWatch(ByVal hwnd As Long)
    DeviceCallBack = SetWindowLong(hwnd, GWL_WNDPROC, AddressOf OnDeviceChange)
End Sub

Public Sub StopUSBWatch(ByVal hwnd As Long)
    DeviceCallBack = SetWindowLong(hwnd, GWL_WNDPROC, DeviceCallBack)
End Sub

Public Function OnDeviceChange(ByVal hwnd As Long, _
    ByVal Msg As Long, _
    ByVal wParam As Long, _
    ByVal lParam As Long) As Long
    
    If (Msg = WM_DEVICECHANGE) Then
        If wParam = DBT_DEVICEARRIVAL Or wParam = DBT_DEVICEREMOVECOMPLETE Then
            'Add your code here
        End If
    End If
    OnDeviceChange = CallWindowProc(DeviceCallBack, hwnd, Msg, wParam, lParam)
End Function

'Form:
Private Sub Form_Load()
    '......
    
    StartUSBWatch Me.hwnd
End Sub

Private Sub Form_Unload(Cancel As Integer)
Dim i As Integer
    StopUSBWatch Me.hwnd

    '......
End Sub