rs232.vb

在vb.net 中如何使用计算机的串口

            Else
                ' Retrieve modem status
                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 _