SerialPort接收问题

#Region "Protected Routines"

        Protected Sub OnCommEventReceived(ByVal source As CommPort, ByVal mask As EventMasks)



            Dim del As CommEventHandler = Me.CommEventEvent

            If (Not del Is Nothing) Then

                Dim SafeInvoker As ISynchronizeInvoke

                Try

                    SafeInvoker = DirectCast(del.Target, ISynchronizeInvoke)

                Catch

                End Try

                If (Not SafeInvoker Is Nothing) Then

                    SafeInvoker.Invoke(del, New Object() {source, mask})

                Else

                    del.Invoke(source, mask)

                End If

            End If

        End Sub

#End Region

        '记日志

        Public Sub SysLog(ByVal strMsg As String)

            Dim strFile As String

            strFile = Now.Year.ToString + Now.Month.ToString + Now.Day.ToString + "client.log"

            Dim objW As New IO.StreamWriter(File.Open(strFile, FileMode.OpenOrCreate))

            objW.Close()

            Dim objWriter As New IO.StreamWriter(File.Open(strFile, FileMode.Append))

            objWriter.WriteLine(strMsg)

            objWriter.Close()

        End Sub

    End Class



#End Region



#Region "Exceptions"

    Public Class CIOChannelException : Inherits ApplicationException



        Sub New(ByVal Message As String)

            MyBase.New(Message)

        End Sub

        Sub New(ByVal Message As String, ByVal InnerException As Exception)

            MyBase.New(Message, InnerException)

        End Sub

    End Class

    Public Class IOTimeoutException : Inherits CIOChannelException



        Sub New(ByVal Message As String)

            MyBase.New(Message)

        End Sub

        Sub New(ByVal Message As String, ByVal InnerException As Exception)

            MyBase.New(Message, InnerException)

        End Sub

    End Class



#End Region

End Namespace

 '得到反回的数据(16进制)

        Overridable ReadOnly Property InputStream() As Byte()

            Get

                Return mabtRxBuf

            End Get

        End Property

        '得到返回的数据(文本)

        Overridable ReadOnly Property InputStreamString() As String

            Get

                Dim oEncoder As New System.Text.ASCIIEncoding

                Dim oEnc As Encoding = Encoding.GetEncoding(1252)

                '-------------------------------------------------------------

                If Not Me.InputStream Is Nothing Then

                    Return oEnc.GetString(Me.InputStream)

                Else

                    Return Nothing

                End If



            End Get

        End Property



        Public Property UseXonXoff() As Boolean

            Get

                Return mbUseXonXoff

            End Get

            Set(ByVal Value As Boolean)

                mbUseXonXoff = Value

            End Set

        End Property

        Public Sub EnableEvents()

            Try

                If mhRS.ToInt32 <= 0 Then

                    Throw New ApplicationException("使用该方法前需要初始化并打开串口")

                Else

                    If moEvents Is Nothing Then

                        mbEnableEvents = True

                        moEvents = New Thread(AddressOf pEventsWatcher)

                        moEvents.IsBackground = True

                        moEvents.Start()

                    End If

                End If

            Catch ex As Exception

                SysLog("CommPort-EnableEvents出现异常:" + ex.Message)

            End Try



        End Sub

        Public Sub DisableEvents()

            Try

                If mbEnableEvents = True Then

                    SyncLock Me

                        mbEnableEvents = False

                    End SyncLock

                    If muOvlE.hEvent.ToInt32 <> 0 Then SetEvent(muOvlE.hEvent)

                    moEvents = Nothing

                End If

            Catch ex As Exception

                SysLog("CommPort-DisableEvents出现异常:" + ex.Message)

            End Try



        End Sub





        Public Sub SetBreak()

            Try

                If mhRS.ToInt32 > 0 Then

                    If SetCommBreak(mhRS) = False Then Throw New Win32Exception

                End If

            Catch ex As Exception

                SysLog("CommPort-SetBreak出现异常:" + ex.Message)

            End Try



        End Sub



        Public Sub ClearBreak()

            Try

                If mhRS.ToInt32 > 0 Then

                    If ClearCommBreak(mhRS) = False Then Throw New Win32Exception

                End If

            Catch ex As Exception

                SysLog("CommPort-ClearBreak出现异常:" + ex.Message)

            End Try

        End Sub

        



#Region "Finalize"

        Protected Overrides Sub Finalize()

            Try

                If Not mbDisposed Then

                    If mbEnableEvents Then Me.DisableEvents()

                    Close()

                End If

            Finally

                MyBase.Finalize()

            End Try

        End Sub

#End Region



#Region "Private Routines"

        Private Sub pSetTimeout()



            Dim uCtm As COMMTIMEOUTS

            If mhRS.ToInt32 <= 0 Then

                Exit Sub

            Else

                With uCtm

                    .ReadIntervalTimeout = 0

                    .ReadTotalTimeoutMultiplier = 0

                    .ReadTotalTimeoutConstant = miTimeout

                    .WriteTotalTimeoutMultiplier = 10

                    .WriteTotalTimeoutConstant = 100

                End With

                SetCommTimeouts(mhRS, uCtm)

            End If

        End Sub

        Private Sub pDispose() Implements IDisposable.Dispose



            If (Not mbDisposed AndAlso (mhRS.ToInt32 > 0)) Then

                Try

                    Me.Close()

                Finally

                    mbDisposed = True

                    GC.SuppressFinalize(Me)

                End Try

            End If





        End Sub

        Private Sub pEventsWatcher()



            'Events to watch

            Dim lMask As EventMasks = EventMasks.Break Or EventMasks.CarrierDetect Or EventMasks.ClearToSend Or _

            EventMasks.DataSetReady Or EventMasks.Ring Or EventMasks.RxChar Or EventMasks.RXFlag Or _

            EventMasks.StatusError

            Dim iBytesRead, iTotBytes, iErrMask As Int32, aBuf As New ArrayList

            Dim uComStat As COMSTAT

            '-----------------------------------

            ' Creates Event

            muOvlE = New OVERLAPPED

            Dim hOvlE As GCHandle = GCHandle.Alloc(muOvlE, GCHandleType.Pinned)

            muOvlE.hEvent = CreateEvent(Nothing, 1, 0, Nothing)

            If muOvlE.hEvent.ToInt32 = 0 Then Throw New ApplicationException("Error creating event for overlapped reading")

            '// Set mask

            SetCommMask(mhRS, lMask)

            '// Looks for RxChar

            While mbEnableEvents = True

                WaitCommEvent(mhRS, lMask, muOvlE)

                Select Case WaitForSingleObject(muOvlE.hEvent, INFINITE)

                    Case WAIT_OBJECT_0

                        '// Event (or abort) detected

                        If mbEnableEvents = False Then Exit While

                        If (lMask And EventMasks.RxChar) > 0 Then

                            '// Read incoming data

                            ClearCommError(mhRS, iErrMask, uComStat)

                            If iErrMask = 0 Then

                                Dim ovl As New OVERLAPPED

                                Dim hOvl As GCHandle = GCHandle.Alloc(ovl, GCHandleType.Pinned)

                                ReDim mabtRxBuf(uComStat.cbInQue - 1)

                                If ReadFile(mhRS, mabtRxBuf, uComStat.cbInQue, iBytesRead, ovl) > 0 Then

                                    If iBytesRead > 0 Then

                                        '// Some bytes read, fills temporary buffer

                                        If iTotBytes < miBufThreshold Then

                                            aBuf.AddRange(mabtRxBuf)

                                            iTotBytes += iBytesRead

                                        End If

                                        '// Threshold reached?, raises event

                                        If iTotBytes >= miBufThreshold Then

                                            '//Copies temp buffer into Rx buffer

                                            ReDim mabtRxBuf(iTotBytes - 1)

                                            aBuf.CopyTo(mabtRxBuf)

                                            '// Raises event

                                            Try

                                                Me.OnCommEventReceived(Me, lMask)

                                            Finally

                                                iTotBytes = 0

                                                aBuf.Clear()

                                            End Try

                                        End If

                                    End If

                                End If

                                If (hOvl.IsAllocated) Then hOvl.Free()

                            End If

                        Else

                            '// Simply raises OnCommEventHandler event

                            Me.OnCommEventReceived(Me, lMask)

                        End If

                    Case Else

                        Dim sErr As String = New Win32Exception().Message

                        Throw New ApplicationException(sErr)

                End Select

            End While

            '// Release Event Handle

            CloseHandle(muOvlE.hEvent)

            muOvlE.hEvent = IntPtr.Zero

            If (hOvlE.IsAllocated) Then hOvlE.Free()

            muOvlE = Nothing

        End Sub







#End Region

        '检测端口状态

        Public Function CheckCom(ByVal CommID As Integer) As Boolean

            Try

                Dim iMode As Int32 = Convert.ToInt32(IIf(meMode = Mode.Overlapped, FILE_FLAG_OVERLAPPED, 0))

                mhRS = CreateFile("\\.\COM" & CommID.ToString, GENERIC_READ Or GENERIC_WRITE, 0, 0, OPEN_EXISTING, iMode, 0)

                If (mhRS.ToInt32 > 0) Then

                    Return True

                Else

                    Return False

                End If

            Catch ex As Exception

                SysLog("CommPort-CheckCom出现异常:" + ex.Message)

                Return False

            End Try

        End Function

        '初始化,并打开端口

        Public Function Open() As Boolean

            '// 以当前数据更新设备数据块

            Dim uDcb As DCB, iRc As Int32

            '// 设置工作模式

            meMode = Mode.Overlapped

            Dim iMode As Int32 = Convert.ToInt32(IIf(meMode = Mode.Overlapped, FILE_FLAG_OVERLAPPED, 0))

            '// 初始化端口



            Try

                '// 创建当前COM口数据流句柄

                mhRS = CreateFile("\\.\COM" & miPort.ToString, GENERIC_READ Or GENERIC_WRITE, 0, 0, OPEN_EXISTING, iMode, 0)

                If (mhRS.ToInt32 > 0) Then

                    '// 清除所有错误

                    Dim lpErrCode As Int32

                    iRc = ClearCommError(mhRS, lpErrCode, New COMSTAT)

                    '// 清除 I/O 缓冲区

                    iRc = PurgeComm(mhRS, PurgeBuffers.RXClear Or PurgeBuffers.TxClear)

                    '// 得到COM设置

                    iRc = GetCommState(mhRS, uDcb)

                    '// 更新设置

                    Dim sParity As String = "NOEM"

                    sParity = sParity.Substring(meParity, 1)

                    '// 设置串口设备数据块状态

                    Dim sDCBState As String = String.Format("baud={0} parity={1} data={2} stop={3}", miBaudRate, sParity, miDataBit, CInt(meStopBit))

                    iRc = BuildCommDCB(sDCBState, uDcb)

                    uDcb.Parity = CByte(meParity)

                    '// 设置Xon/Xoff(发送机)状态

                    If mbUseXonXoff Then

                        uDcb.Bits1 = 768

                    Else

                        uDcb.Bits1 = 0

                    End If

                    iRc = SetCommState(mhRS, uDcb)

                    If iRc = 0 Then

                        Dim sErrTxt As String = New Win32Exception().Message

                        Throw New CIOChannelException("Unable to set COM state " & sErrTxt)

                    End If

                    '// 缓冲 (Rx,Tx)会话模式

                    iRc = SetupComm(mhRS, miBufferSize, miBufferSize)

                    '// 设置超时

                    pSetTimeout()

                    '//触发事件

                    If mbEnableEvents Then Me.EnableEvents()

                    Return True

                Else

                    Return False

                End If

            Catch Ex As Exception

                '一般性错误

                SysLog("CommPort-Open出现异常:" + Ex.Message)

                Return False

            End Try

        End Function

        '关闭端口

        Public Sub Close()

            Try

                If mhRS.ToInt32 > 0 Then

                    If mbEnableEvents = True Then

                        Me.DisableEvents()

                    End If

                    Dim ret As Boolean = CloseHandle(mhRS)

                    If Not ret Then Throw New Win32Exception

                    mhRS = New IntPtr(0)

                End If

            Catch ex As Exception

                SysLog("CommPort-Close出现异常:" + ex.Message)

            End Try



        End Sub

        '返回串口状态

        ReadOnly Property IsOpen() As Boolean

            Get

                Return CBool(mhRS.ToInt32 > 0)

            End Get

        End Property

        '写数据

        Private Sub WriteValue(ByVal Buffer As Byte())

            Dim iRc, iBytesWritten As Integer, hOvl As GCHandle

            '-----------------------------------------------------------------

            muOvlW = New OVERLAPPED

            If mhRS.ToInt32 <= 0 Then

                Throw New ApplicationException("Please initialize and open port before using this method")

            Else

                '// 创建事件

                Try

                    hOvl = GCHandle.Alloc(muOvlW, GCHandleType.Pinned)

                    muOvlW.hEvent = CreateEvent(Nothing, 1, 0, Nothing)

                    If muOvlW.hEvent.ToInt32 = 0 Then Throw New ApplicationException("Error creating event for overlapped writing")

                    '// 清除 IO 缓冲区,并发送数据

                    iRc = WriteFile(mhRS, Buffer, Buffer.Length, 0, muOvlW)

                    If iRc = 0 Then

                        If Marshal.GetLastWin32Error <> ERROR_IO_PENDING Then

                            Throw New ApplicationException("Write command error")

                        Else

                            'Tx

                            If GetOverlappedResult(mhRS, muOvlW, iBytesWritten, 1) = 0 Then

                                Throw New ApplicationException("Write pending error")

                            Else

                                '//是否发送所有数据

                                If iBytesWritten <> Buffer.Length Then Throw New ApplicationException("Write Error - Bytes Written " & iBytesWritten.ToString & " of " & Buffer.Length.ToString)

                            End If

                        End If

                    End If

                Catch ex As Exception

                    SysLog("CommPort-WriteValue出现异常:" + ex.Message)

                Finally

                    '关闭句柄

                    CloseHandle(muOvlW.hEvent)

                    If (hOvl.IsAllocated = True) Then hOvl.Free()

                End Try

            End If

        End Sub

        '写数据 

        'isHex:是否以十六进制发送,默认以十六进制发送

        Sub SendCommand(ByVal Buffer As String, Optional ByVal meWriteMode As WriteMode = WriteMode.HexData)

            Dim oEncoder As New System.Text.ASCIIEncoding

            Dim oEnc As Encoding = Encoding.GetEncoding(1252)

            '-------------------------------------------------------------

            Dim aByte() As Byte

            Dim i As Integer

            Try

                If meWriteMode = WriteMode.HexData Then

                    i = Buffer.Length / 2 - 1

                    ReDim aByte(i)

                    For i = 0 To i

                        aByte(i) = "&H" & Mid(Buffer, i * 2 + 1, 2)

                    Next

                Else

                    aByte = oEnc.GetBytes(Buffer)

                End If

                Me.WriteValue(aByte)

            Catch ex As Exception

                SysLog("CommPort-SendCommand出现异常:" + ex.Message)

            End Try

        End Sub



        '读数据，返回长度

        Public Function Read(ByVal Bytes2Read As Integer) As Integer

            Dim iReadChars, iRc As Integer, hOvl As GCHandle

            If Bytes2Read = 0 Then Bytes2Read = miBufferSize

            muOvlR = New OVERLAPPED

            If mhRS.ToInt32 <= 0 Then

                Throw New ApplicationException("使用该方法前需要初始化并打开串口")

            Else

                '得到字节

                Try

                    GCHandle.Alloc(muOvlR, GCHandleType.Pinned)

                    muOvlR.hEvent = CreateEvent(Nothing, 1, 0, Nothing)

                    If muOvlR.hEvent.ToInt32 = 0 Then Throw New ApplicationException("重置事件失败")

                    '清除 IO缓冲区并且读出数据

                    ReDim mabtRxBuf(Bytes2Read - 1)

                    iRc = ReadFile(mhRS, mabtRxBuf, Bytes2Read, iReadChars, muOvlR)

                    If iRc = 0 Then

                        If Marshal.GetLastWin32Error() <> ERROR_IO_PENDING Then

                            Throw New ApplicationException("读失败")

                        Else

                            '待复制的字符

                            iRc = WaitForSingleObject(muOvlR.hEvent, miTimeout)

                            Select Case iRc

                                Case WAIT_OBJECT_0

                                    '得到数据……

                                    If GetOverlappedResult(mhRS, muOvlR, iReadChars, 0) = 0 Then

                                        Throw New ApplicationException("读失败")

                                    Else

                                        Return iReadChars

                                    End If

                                Case WAIT_TIMEOUT

                                    Throw New IOTimeoutException("读超时")

                                Case Else

                                    Throw New ApplicationException("其它未知读错误")

                            End Select

                        End If

                    Else

                        Return (iReadChars)

                    End If

                Catch ex As Exception

                    SysLog("CommPort-SendCommand出现异常:" + ex.Message)

                Finally

                    '关闭

                    CloseHandle(muOvlR.hEvent)

                    If (hOvl.IsAllocated) Then hOvl.Free()

                End Try

            End If

        End Function

#Region "Win32API"

        '// Win32 API

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function SetCommState(ByVal hCommDev As IntPtr, ByRef lpDCB As DCB) As Int32

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function GetCommState(ByVal hCommDev As IntPtr, ByRef lpDCB As DCB) As Int32

        End Function

        <DllImport("kernel32.dll", SetlastError:=True, CharSet:=CharSet.Auto)> Private Shared Function BuildCommDCB(ByVal lpDef As String, ByRef lpDCB As DCB) As Int32

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function SetupComm(ByVal hFile As IntPtr, ByVal dwInQueue As Int32, ByVal dwOutQueue As Int32) As Int32

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function SetCommTimeouts(ByVal hFile As IntPtr, ByRef lpCommTimeouts As COMMTIMEOUTS) As Int32

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function GetCommTimeouts(ByVal hFile As IntPtr, ByRef lpCommTimeouts As COMMTIMEOUTS) As Int32

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function ClearCommError(ByVal hFile As IntPtr, ByRef lpErrors As Int32, ByRef lpComStat As COMSTAT) As Int32

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function PurgeComm(ByVal hFile As IntPtr, ByVal dwFlags As Int32) As Int32

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function EscapeCommFunction(ByVal hFile As IntPtr, ByVal ifunc As Int32) As Boolean

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function WaitCommEvent(ByVal hFile As IntPtr, ByRef Mask As EventMasks, ByRef lpOverlap As OVERLAPPED) As Int32

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function WriteFile(ByVal hFile As IntPtr, ByVal Buffer As Byte(), ByVal nNumberOfBytesToWrite As Integer, ByRef lpNumberOfBytesWritten As Integer, ByRef lpOverlapped As OVERLAPPED) As Integer

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function ReadFile(ByVal hFile As IntPtr, <Out()> ByVal Buffer As Byte(), ByVal nNumberOfBytesToRead As Integer, ByRef lpNumberOfBytesRead As Integer, ByRef lpOverlapped As OVERLAPPED) As Integer

        End Function

        <DllImport("kernel32.dll", SetlastError:=True, CharSet:=CharSet.Auto)> Private Shared Function CreateFile(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 IntPtr

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function CloseHandle(ByVal hObject As IntPtr) As Boolean

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Public Shared Function GetCommModemStatus(ByVal hFile As IntPtr, ByRef lpModemStatus As Int32) As Boolean

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function SetEvent(ByVal hEvent As IntPtr) As Boolean

        End Function

        <DllImport("kernel32.dll", SetlastError:=True, CharSet:=CharSet.Auto)> Private Shared Function CreateEvent(ByVal lpEventAttributes As IntPtr, ByVal bManualReset As Int32, ByVal bInitialState As Int32, ByVal lpName As String) As IntPtr

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function WaitForSingleObject(ByVal hHandle As IntPtr, ByVal dwMilliseconds As Int32) As Int32

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function GetOverlappedResult(ByVal hFile As IntPtr, ByRef lpOverlapped As OVERLAPPED, ByRef lpNumberOfBytesTransferred As Int32, ByVal bWait As Int32) As Int32

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function SetCommMask(ByVal hFile As IntPtr, ByVal lpEvtMask As Int32) As Int32

        End Function

        <DllImport("kernel32.dll", SetlastError:=True, CharSet:=CharSet.Auto)> Private Shared Function GetDefaultCommConfig(ByVal lpszName As String, ByRef lpCC As COMMCONFIG, ByRef lpdwSize As Integer) As Boolean

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function SetCommBreak(ByVal hFile As IntPtr) As Boolean

        End Function

        <DllImport("kernel32.dll", SetlastError:=True)> Private Shared Function ClearCommBreak(ByVal hFile As IntPtr) As Boolean

        End Function





#End Region



#Region "事件"

        Public Event CommEvent As CommEventHandler

#End Region



#Region "委托"

        Public Delegate Sub CommEventHandler(ByVal source As CommPort, ByVal Mask As EventMasks)

#End Region



#Region "属性"

        Public Property Port() As Integer

            Get

                Return miPort

            End Get

            Set(ByVal Value As Integer)

                miPort = Value

            End Set

        End Property

        '清理通信缓冲区

        Public Sub PurgeBuffer(ByVal Mode As PurgeBuffers)

            If (mhRS.ToInt32 > 0) Then PurgeComm(mhRS, Mode)

        End Sub

        Public Overridable Property Timeout() As Integer

            Get

                Return miTimeout

            End Get

            Set(ByVal Value As Integer)

                miTimeout = CInt(IIf(Value = 0, 500, Value))

                '//如果端口打开,更改状态为忙

                pSetTimeout()

            End Set

        End Property

        '端口的奇偶

        Public Property Parity() As DataParity

            Get

                Return meParity

            End Get

            Set(ByVal Value As DataParity)

                meParity = Value

            End Set

        End Property

        '停止位

        Public Property StopBit() As DataStopBit

            Get

                Return meStopBit

            End Get

            Set(ByVal Value As DataStopBit)

                meStopBit = Value

            End Set

        End Property

        '波特率

        Public Property BaudRate() As Integer

            Get

                Return miBaudRate

            End Get

            Set(ByVal Value As Integer)

                miBaudRate = Value

            End Set

        End Property

        '数据位

        Public Property DataBit() As Integer

            Get

                Return miDataBit

            End Get

            Set(ByVal Value As Integer)

                miDataBit = Value

            End Set

        End Property

        '得到缓冲区大小

        Public Property BufferSize() As Integer

            Get

                Return miBufferSize

            End Get

            Set(ByVal Value As Integer)

                miBufferSize = Value

            End Set

        End Property

#End Region

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

''''命名空间：JustinIO

''''类名：　　CommPort

''''类说明：　考虑到标准组件操控性能不强，因此利用API对RS232通讯全封装

''''作者：    Cong Wenchao

''''时间：    2007,11,3

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

Imports System

Imports System.Runtime.InteropServices

Imports System.Text

Imports System.Threading

Imports System.ComponentModel

Imports System.IO

Namespace JustinIO

#Region "CommPort"

    Public Class CommPort : Implements IDisposable



#Region "类成员"

        Private mhRS As IntPtr = New IntPtr(0)                      'COM句柄							

        Private miPort As Integer = 1                               '默认打开COM1	

        Private miTimeout As Int32 = 70                             '超时设置

        Private miBaudRate As Int32 = 115200

        Private meParity As DataParity = 0

        Private meStopBit As DataStopBit = 0

        Private miDataBit As Int32 = 8

        Private miBufferSize As Int32 = 512                         '缓冲区大小

        Private mabtRxBuf As Byte()                                 '返回缓冲区数值	

        Private meMode As Mode                                      '工作模式

        Private moEvents As Thread

        Private mbDisposed As Boolean

        Private mbUseXonXoff As Boolean

        Private mbEnableEvents As Boolean

        Private miBufThreshold As Int32 = 1

        Private muOvlE As OVERLAPPED

        Private muOvlW As OVERLAPPED

        Private muOvlR As OVERLAPPED

#End Region



#Region "Enums"

        '奇偶值

        Public Enum DataParity

            Parity_None = 0

            Parity_Odd

            Parity_Even

            Parity_Mark

        End Enum

        '停止位

        Public Enum DataStopBit

            StopBit_1 = 1

            StopBit_2

        End Enum

        '清理缓冲区

        <Flags()> Public Enum PurgeBuffers

            RXAbort = &H2

            RXClear = &H8

            TxAbort = &H1

            TxClear = &H4

        End Enum

        Private Enum Lines

            SetRts = 3

            ClearRts = 4

            SetDtr = 5

            ClearDtr = 6

            ResetDev = 7        '如果可能的话,重启

            SetBreak = 8        '设置中断

            ClearBreak = 9      '清除中断

        End Enum

        '状态

        <Flags()> Public Enum ModemStatusBits

            ClearToSendOn = &H10

            DataSetReadyOn = &H20

            RingIndicatorOn = &H40

            CarrierDetect = &H80

        End Enum

        '工作模式

        Public Enum Mode

            NonOverlapped

            Overlapped

        End Enum

        '事件枚举

        <Flags()> Public Enum EventMasks

            RxChar = &H1

            RXFlag = &H2

            TxBufferEmpty = &H4

            ClearToSend = &H8

            DataSetReady = &H10

            CarrierDetect = &H20

            Break = &H40

            StatusError = &H80

            Ring = &H100

        End Enum

        '写数据的模式

        Public Enum WriteMode

            HexData = 0

            DecimalData = 1

        End Enum

#End Region



#Region "结构体"

        <StructLayout(LayoutKind.Sequential, Pack:=1)> Private Structure DCB

            Public DCBlength As Int32

            Public BaudRate As Int32

            Public Bits1 As Int32

            Public wReserved As Int16

            Public XonLim As Int16

            Public XoffLim As Int16

            Public ByteSize As Byte

            Public Parity As Byte

            Public StopBits As Byte

            Public XonChar As Char

            Public XoffChar As Char

            Public ErrorChar As Char

            Public EofChar As Char

            Public EvtChar As Char

            Public wReserved2 As Int16

        End Structure

        <StructLayout(LayoutKind.Sequential, Pack:=1)> Private Structure COMMTIMEOUTS

            Public ReadIntervalTimeout As Int32

            Public ReadTotalTimeoutMultiplier As Int32

            Public ReadTotalTimeoutConstant As Int32

            Public WriteTotalTimeoutMultiplier As Int32

            Public WriteTotalTimeoutConstant As Int32

        End Structure

        <StructLayout(LayoutKind.Sequential, Pack:=8)> Private Structure COMMCONFIG

            Public dwSize As Int32

            Public wVersion As Int16

            Public wReserved As Int16

            Public dcbx As DCB

            Public dwProviderSubType As Int32

            Public dwProviderOffset As Int32

            Public dwProviderSize As Int32

            Public wcProviderData As Int16

        End Structure

        <StructLayout(LayoutKind.Sequential, Pack:=1)> Public Structure OVERLAPPED

            Public Internal As Int32

            Public InternalHigh As Int32

            Public Offset As Int32

            Public OffsetHigh As Int32

            Public hEvent As IntPtr

        End Structure

        <StructLayout(LayoutKind.Sequential, Pack:=1)> Private Structure COMSTAT

            Dim fBitFields As Int32

            Dim cbInQue As Int32

            Dim cbOutQue As Int32

        End Structure



#End Region



#Region "常量"

        Private Const PURGE_RXABORT As Integer = &H2

        Private Const PURGE_RXCLEAR As Integer = &H8

        Private Const PURGE_TXABORT As Integer = &H1

        Private Const PURGE_TXCLEAR As Integer = &H4

        Private Const GENERIC_READ As Integer = &H80000000

        Private Const GENERIC_WRITE As Integer = &H40000000

        Private Const OPEN_EXISTING As Integer = 3

        Private Const INVALID_HANDLE_VALUE As Integer = -1

        Private Const IO_BUFFER_SIZE As Integer = 1024

        Private Const FILE_FLAG_OVERLAPPED As Int32 = &H40000000

        Private Const ERROR_IO_PENDING As Int32 = 997

        Private Const WAIT_OBJECT_0 As Int32 = 0

        Private Const ERROR_IO_INCOMPLETE As Int32 = 996

        Private Const WAIT_TIMEOUT As Int32 = &H102&

        Private Const INFINITE As Int32 = &HFFFFFFFF

#End Region

Public Class Form1



    Dim buffB(30) As Byte  '串口接收缓冲区 如果接收字符很长最好设的大点



    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load



        SerialPort1.BaudRate = 9600 '波特率设为9600

        SerialPort1.PortName = "com1" '端口为串口1



        If SerialPort1.IsOpen = False Then SerialPort1.Open() '打开串口

    End Sub



    Private Sub SerialPort1_DataReceived(ByVal sender As System.Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived

        SerialPort1.Read(buffB, 0, 30)

        BeginInvoke(New EventHandler(AddressOf ONMLoadA), SerialPort1.BytesToRead()) '使用委托方式显示接收到的字符串

    End Sub



    Sub ONMLoadA(ByVal sender As System.Object, ByVal e As System.EventArgs)

        'TextBox1.Text = Encoding.ASCII.GetString(buffB, 0, 30) '显示ASCII单字节字符

        TextBox1.Text = Encoding.Default.GetString(buffB, 0, 30) '显示汉字

    End Sub



    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        SerialPort1.Write("test") '发送字符串

    End Sub

End Class