串口編程

Question

我的要求是沒有檢出任何通信設備連接

也到哪個端口我們如何才能增加它可以安裝我的包一起安裝在包中的任何通信設備的驅動程序

Answer 1

Option Explicit 
'****************************************************************************** 
' Description: Scans machine using the WIN32 API for all available comm hardware 
' Usage: main program calls the 'CommSettings' sub, passing the 
'   name of the communications control and a combobox name. 
'****************************************************************************** 

Dim CommCntrl    As Control         ' the communications control 
Dim cmboPort    As Control         ' combobox to populate 
Dim bNoComm    As Boolean 

Private Const MAX_COMM = 16           ' 32 max port # to check 

Private Const GENERIC_READ = &H80000000 
Private Const GENERIC_WRITE = &H40000000 
Private Const OPEN_EXISTING = 3 
Private Const FILE_FLAG_OVERLAPPED = &H40000000 
Private Const INVALID_HANDLE_VALUE = -1 

Private Declare Function CreateFile Lib "kernel32" Alias "CreateFileA" _ 
            (ByVal lpFileName As String, _ 
            ByVal dwDesiredAccess As Long, _ 
            ByVal dwShareMode As Long, _ 
            ByVal lpSecurityAttributes As String, _ 
            ByVal dwCreationDisposition As Long, _ 
            ByVal dwFlagsAndAttributes As Long, _ 
            ByVal hTemplateFile As String) As Long 

Private Declare Function CloseHandle Lib "kernel32" (_ 
            ByVal hObject As Long) As Long 


Public Sub GetPorts(serialCntrl As Control, comboBox As Control) 
    '****************************************************************************** 
    ' Usage: Pass the name of the communications control, a combo box, and the 
    '   current com port setting in the calling routine. 
    '****************************************************************************** 

    Dim iCntr    As Integer         ' loop counter 
    Dim hRet    As Long          ' api return value 
    Dim sCom    As String         ' comm port name 

    On Error Resume Next 

    Set cmboPort = comboBox 

    Set CommCntrl = serialCntrl 
    Err = 0 

    cmboPort.Clear 

    ' Close the port if it's open 
    If CommCntrl.PortOpen = True Then 
     CommCntrl.PortOpen = False 
     DoEvents 
    Else 
     bNoComm = True 
    End If 

    ' Scan for all possible hardware so we can display all available ports 
    ' in the combo box. Dynamically adjusts for PC's with addin cards 
    For iCntr = 1 To MAX_COMM 
     ' try to open the port. 
     ' \\.\ required for ports > 9, works for all ports 
     sCom = "\\.\Com" & CStr(iCntr) & vbNullChar 
     hRet = CreateFile(sCom, GENERIC_READ Or _ 
           GENERIC_WRITE, 0, vbNullString, OPEN_EXISTING, _ 
          FILE_FLAG_OVERLAPPED, vbNullString) 

     If hRet <> INVALID_HANDLE_VALUE Then 
      hRet = CloseHandle(hRet) 
      cmboPort.AddItem Format$(iCntr) 
      Debug.Print iCntr 
     Else 
      ' dll error 5 = already open 
      ' dll error 2 = no harware 
      If Err.LastDllError = 5 Then 
       cmboPort.AddItem Format$(iCntr) & " - Busy" 
      End If 
     End If 
    Next 

End Sub