rs232.vb

使用vb.net实现串口通讯的过程

                Dim lpModemStatus As Integer
                If Not GetCommModemStatus(mhRS, lpModemStatus) Then
                    Throw New ApplicationException("Unable to get modem status")
                Else
                    Return CType(lpModemStatus, ModemStatusBits)
                End If
            End If
        End Get
    End Property

    ' This property gets or sets the Parity
    Public Property Parity() As DataParity
        Get
            Return meParity
        End Get
        Set(ByVal Value As DataParity)
            meParity = Value
        End Set
    End Property

    ' This property gets or sets the Port
    Public Property Port() As Integer
        Get
            Return miPort
        End Get
        Set(ByVal Value As Integer)
            miPort = Value
        End Set
    End Property

    ' This write-only property sets or resets the RTS line.
    Public WriteOnly Property Rts() As Boolean
        Set(ByVal Value As Boolean)
            If Not mhRS = -1 Then
                If Value Then
                    EscapeCommFunction(mhRS, Lines.SetRts)
                Else
                    EscapeCommFunction(mhRS, Lines.ClearRts)
                End If
            End If
        End Set
    End Property

    ' This property gets or sets the StopBit
    Public Property StopBit() As DataStopBit
        Get
            Return meStopBit
        End Get
        Set(ByVal Value As DataStopBit)
            meStopBit = Value
        End Set
    End Property

    ' This property gets or sets the Timeout
    Public Overridable Property Timeout() As Integer
        Get
            Return miTimeout
        End Get
        Set(ByVal Value As Integer)
            miTimeout = CInt(IIf(Value = 0, 500, Value))
            ' If Port is open updates it on the fly
            pSetTimeout()
        End Set
    End Property

    ' This property gets or sets the working mode to overlapped
    '   or non-overlapped.
    Public Property WorkingMode() As Mode
        Get
            Return meMode
        End Get
        Set(ByVal Value As Mode)
            meMode = Value
        End Set
    End Property

#End Region


#Region "Win32API"
    ' The following functions are the required Win32 functions needed to 
    '   make communication with the Comm Port possible.

    <DllImport("kernel32.dll")> Private Shared Function BuildCommDCB( _
        ByVal lpDef As String, ByRef lpDCB As DCB) As Integer
    End Function

    <DllImport("kernel32.dll")> Private Shared Function ClearCommError( _
        ByVal hFile As Integer, ByVal lpErrors As Integer, _
        ByVal l As Integer) As Integer
    End Function

    <DllImport("kernel32.dll")> Private Shared Function CloseHandle( _
        ByVal hObject As Integer) As Integer
    End Function

    <DllImport("kernel32.dll")> Private Shared Function CreateEvent( _
        ByVal lpEventAttributes As Integer, ByVal bManualReset As Integer, _
        ByVal bInitialState As Integer, _
        <MarshalAs(UnmanagedType.LPStr)> ByVal lpName As String) As Integer
    End Function

    <DllImport("kernel32.dll")> Private Shared Function CreateFile( _
        <MarshalAs(UnmanagedType.LPStr)> ByVal lpFileName As String, _
        ByVal dwDesiredAccess As Integer, ByVal dwShareMode As Integer, _
        ByVal lpSecurityAttributes As Integer, _
        ByVal dwCreationDisposition As Integer, _
        ByVal dwFlagsAndAttributes As Integer, _
        ByVal hTemplateFile As Integer) As Integer
    End Function

    <DllImport("kernel32.dll")> Private Shared Function EscapeCommFunction( _
        ByVal hFile As Integer, ByVal ifunc As Long) As Boolean
    End Function

    <DllImport("kernel32.dll")> Private Shared Function FormatMessage( _
        ByVal dwFlags As Integer, ByVal lpSource As Integer, _
        ByVal dwMessageId As Integer, ByVal dwLanguageId As Integer, _
        <MarshalAs(UnmanagedType.LPStr)> ByVal lpBuffer As String, _
        ByVal nSize As Integer, ByVal Arguments As Integer) As Integer
    End Function

    Private Declare Function FormatMessage Lib "kernel32" Alias _
     "FormatMessageA" (ByVal dwFlags As Integer, ByVal lpSource As Integer, _
     ByVal dwMessageId As Integer, ByVal dwLanguageId As Integer, _
     ByVal lpBuffer As StringBuilder, ByVal nSize As Integer, _
     ByVal Arguments As Integer) As Integer

    <DllImport("kernel32.dll")> Public Shared Function GetCommModemStatus( _
        ByVal hFile As Integer, ByRef lpModemStatus As Integer) As Boolean
    End Function

    <DllImport("kernel32.dll")> Private Shared Function GetCommState( _
        ByVal hCommDev As Integer, ByRef lpDCB As DCB) As Integer
    End Function

    <DllImport("kernel32.dll")> Private Shared Function GetCommTimeouts( _
        ByVal hFile As Integer, ByRef lpCommTimeouts As COMMTIMEOUTS) As Integer
    End Function

    <DllImport("kernel32.dll")> Private Shared Function GetLastError() As Integer
    End Function

    <DllImport("kernel32.dll")> Private Shared Function GetOverlappedResult( _
        ByVal hFile As Integer, ByRef lpOverlapped As OVERLAPPED, _
        ByRef lpNumberOfBytesTransferred As Integer, _
        ByVal bWait As Integer) As Integer
    End Function

    <DllImport("kernel32.dll")> Private Shared Function PurgeComm( _
        ByVal hFile As Integer, ByVal dwFlags As Integer) As Integer
    End Function

    <DllImport("kernel32.dll")> Private Shared Function ReadFile( _
        ByVal hFile As Integer, ByVal Buffer As Byte(), _
        ByVal nNumberOfBytesToRead As Integer, _
        ByRef lpNumberOfBytesRead As Integer, _
        ByRef lpOverlapped As OVERLAPPED) As Integer
    End Function

    <DllImport("kernel32.dll")> Private Shared Function SetCommTimeouts( _
        ByVal hFile As Integer, ByRef lpCommTimeouts As COMMTIMEOUTS) As Integer
    End Function

    <DllImport("kernel32.dll")> Private Shared Function SetCommState( _
        ByVal hCommDev As Integer, ByRef lpDCB As DCB) As Integer
    End Function

    <DllImport("kernel32.dll")> Private Shared Function SetupComm( _
        ByVal hFile As Integer, ByVal dwInQueue As Integer, _
        ByVal dwOutQueue As Integer) As Integer
    End Function

    <DllImport("kernel32.dll")> Private Shared Function SetCommMask( _
        ByVal hFile As Integer, ByVal lpEvtMask As Integer) As Integer
    End Function

    <DllImport("kernel32.dll")> Private Shared Function WaitCommEvent( _
        ByVal hFile As Integer, ByRef Mask As EventMasks, _
        ByRef lpOverlap As OVERLAPPED) As Integer
    End Function

    <DllImport("kernel32.dll")> Private Shared Function WaitForSingleObject( _
        ByVal hHandle As Integer, ByVal dwMilliseconds As Integer) As Integer
    End Function

    <DllImport("kernel32.dll")> Private Shared Function WriteFile( _
        ByVal hFile As Integer, ByVal Buffer As Byte(), _
        ByVal nNumberOfBytesToWrite As Integer, _
        ByRef lpNumberOfBytesWritten As Integer, _
        ByRef lpOverlapped As OVERLAPPED) As Integer
    End Function

#End Region

#Region "Methods"

    ' This subroutine invokes a thread to perform an asynchronous read.
    '   This routine should not be called directly, but is used
    '   by the class.
    Public Sub _R()
        Dim iRet As Integer = Read(miTmpBytes2Read)
    End Sub

    ' This subroutine invokes a thread to perform an asynchronous write.
    '   This routine should not be called directly, but is used
    '   by the class.
    Public Sub _W()
        Write(mabtTmpTxBuf)
    End Sub

    ' This subroutine uses another thread to read from the Comm Port. It 
    '   raises RxCompleted when done. It reads an integer.
    Public Overloads Sub AsyncRead(ByVal Bytes2Read As Integer)
        If meMode <> Mode.Overlapped Then Throw New ApplicationException( _
            "Async Methods allowed only when WorkingMode=Overlapped")
        miTmpBytes2Read = Bytes2Read
        moThreadTx = New Thread(AddressOf _R)
        moThreadTx.Start()
    End Sub

    ' This subroutine uses another thread to write to the Comm Port. It 
    '   raises TxCompleted when done. It writes an array of bytes.
    Public Overloads Sub AsyncWrite(ByVal Buffer() As Byte)
        If meMode <> Mode.Overlapped Then Throw New ApplicationException( _
            "Async Methods allowed only when WorkingMode=Overlapped")
        If mbWaitOnWrite = True Then Throw New ApplicationException( _
            "Unable to send message because of pending transmission.")
        mabtTmpTxBuf = Buffer
        moThreadTx = New Thread(AddressOf _W)
        moThreadTx.Start()
    End Sub

    ' This subroutine uses another thread to write to the Comm Port. It 
    '   raises TxCompleted when done. It writes a string.
    Public Overloads Sub AsyncWrite(ByVal Buffer As String)
        Dim oEncoder As New System.Text.ASCIIEncoding()
        Dim aByte() As Byte = oEncoder.GetBytes(Buffer)
        Me.AsyncWrite(aByte)
    End Sub

    ' This function takes the ModemStatusBits and returns a boolean value
    '   signifying whether the Modem is active.
    Public Function CheckLineStatus(ByVal Line As ModemStatusBits) As Boolean
        Return Convert.ToBoolean(ModemStatus And Line)
    End Function

    ' This subroutine clears the input buffer.
    Public Sub ClearInputBuffer()
        If Not mhRS = -1 Then
            PurgeComm(mhRS, PURGE_RXCLEAR)
        End If
    End Sub

    ' This subroutine closes the Comm Port.
    Public Sub Close()
        If mhRS <> -1 Then
            CloseHandle(mhRS)
            mhRS = -1
        End If
    End Sub

    ' This subroutine opens and initializes the Comm Port
    Public Overloads Sub Open()
        ' Get Dcb block,Update with current data
        Dim uDcb As DCB, iRc As Integer
        ' Set working mode
        Dim iMode As Integer = Convert.ToInt32(IIf(meMode = Mode.Overlapped, _
            FILE_FLAG_OVERLAPPED, 0))
        ' Initializes Com Port
        If miPort > 0 Then
            Try
                ' Creates a COM Port stream handle 
                mhRS = CreateFile("COM" & miPort.ToString, _
                GENERIC_READ Or GENERIC_WRITE, 0, 0, _
                OPEN_EXISTING, iMode, 0)
                If mhRS <> -1 Then
                    ' Clear all comunication errors
                    Dim lpErrCode As Integer
                    iRc = ClearCommError(mhRS, lpErrCode, 0&)
                    ' Clears I/O buffers
                    iRc = PurgeComm(mhRS, PurgeBuffers.RXClear Or _
                        PurgeBuffers.TxClear)
                    ' Gets COM Settings