VB.NET使用readfile和writefile读写串口数据问题

[sgmcumt]

如题我引用win32中的读写函数对串口进行读写，总是出现读写错误，如图

相关代码如下

 Public Declare Auto Function WriteFile Lib "kernel32.dll" (ByVal hFile As Integer, ByVal Buffer As Byte(), ByVal nNumberOfBytesToWrite As Integer, ByRef lpNumberOfBytesWritten As Integer, ByRef lpOverlapped As Overlapped) As Integer
Public Declare Auto Function ReadFile Lib "kernel32.dll" (ByVal hFile As Integer, ByVal Buffer As Byte(), ByVal nNumberOfBytesToRead As Integer, ByRef lpNumberOfBytesRead As Integer, ByRef lpOverlapped As Overlapped) As Integer
   

其中最后一项定义的Overlapped结构，定义如下

    <StructLayout(LayoutKind.Sequential, Pack:=1)> Public Structure OVERLAPPED
        Public Internal As Integer
        Public InternalHigh As Integer
        Public Offset As Integer
        Public OffsetHigh As Integer
        Public hEvent As Integer
    End Structure

其中读写函数如下

    '******************************************
    '将字节数据传送出去
    '重载函数之一，需传入字节数组
    '******************************************
    Public Sub Write(ByVal Buffer As Byte())
        Dim iBytesWritten, iRc As Integer
        Dim WriteOverlapped As OVERLAPPED
        ' WriteOverlapped.Internal = 0
        '---------------------------------

        If mhRS = -1 Then
            Throw New ApplicationException("必须先打开通信端口，才能作输出。")
        Else
            Try
                iRc = WriteFile(mhRS, Buffer, Buffer.Length, iBytesWritten, WriteOverlapped) '输出数组
                If iRc = 0 Then
                    Throw New ApplicationException("传输失败 已传输" & iBytesWritten.ToString & " Bytes/传输" & Buffer.Length.ToString & "Bytes")
                End If
            Catch Ex As Exception
                MsgBox(Ex.ToString)
            End Try
        End If
    End Sub

    '******************************************
    '将字节数据传送出去
    '重载函数之一，需传入字符串
    '首先将字符串分解成数组，以便WriteFile函数可以使用
    '******************************************
    Public Sub Write(ByVal Buffer As String)
        Dim oEncoder As New System.Text.UTF8Encoding
        Dim aByte() As Byte = oEncoder.GetBytes(Buffer)
        Write(aByte) '调用另一个传输的重载函数
    End Sub

    '******************************************
    '将字节数据接收进来
    '重载函数之一，第一个参数是读取的字节数，第二个参数是返回的字节数组
    '如果传入的参数使用ByVal，原始的数据将不会被更改，故在此需用ByRef
    '在调用的地方才能得到此函数所在返回的结果
    '******************************************
    Public Sub Read(ByRef Bytes2Read As Integer, ByRef InputByte() As Byte)
        Dim iReadChars, iRc, lpErrors As Integer
        Dim mabtRxBuf As Byte()             '接收缓冲区
        Dim ReadOverlapped As OVERLAPPED
        '设置读取数据的长度
        If mhRS = -1 Then
            Throw New ApplicationException("尚未打开通信端口，不能读取数据!")
        Else
            '读取字节
            Try
                Dim cs As COMSTAT
                ClearCommError(mhRS, lpErrors, cs)  '取得缓冲区的字节数
                iReadChars = cs.cbInQue
                ReDim mabtRxBuf(iReadChars - 1)
                iRc = ReadFile(mhRS, mabtRxBuf, cs.cbInQue, iReadChars, ReadOverlapped )
                If iRc = 0 Then
                    '读取错误
                    Throw New ApplicationException("读取错误： " & iRc.ToString)
                Else
                    Bytes2Read = iReadChars
                    InputByte = mabtRxBuf
                End If
            Catch Ex As Exception
                '其他的读取错误状态
                Throw New ApplicationException("读取错误： " & Ex.Message, Ex)
            End Try
        End If
    End Sub

运行之后，无法读写数据，如果把overlapped更改为integer就可以，代码如下

    Public Declare Auto Function WriteFile Lib "kernel32.dll" (ByVal hFile As Integer, ByVal Buffer As Byte(), ByVal nNumberOfBytesToWrite As Integer, ByRef lpNumberOfBytesWritten As Integer, ByRef lpOverlapped As Integer) As Integer
Public Declare Auto Function ReadFile Lib "kernel32.dll" (ByVal hFile As Integer, ByVal Buffer As Byte(), ByVal nNumberOfBytesToRead As Integer, ByRef lpNumberOfBytesRead As Integer, ByRef lpOverlapped As Integer) As Integer
    '******************************************
    '将字节数据传送出去
    '重载函数之一，需传入字节数组
    '******************************************
    Public Sub Write(ByVal Buffer As Byte())
        Dim iBytesWritten, iRc As Integer
        Dim WriteOverlapped As OVERLAPPED
        ' WriteOverlapped.Internal = 0
        '---------------------------------

        If mhRS = -1 Then
            Throw New ApplicationException("必须先打开通信端口，才能作输出。")
        Else
            Try
                iRc = WriteFile(mhRS, Buffer, Buffer.Length, iBytesWritten, Nothing) '输出数组
                If iRc = 0 Then
                    Throw New ApplicationException("传输失败 已传输" & iBytesWritten.ToString & " Bytes/传输" & Buffer.Length.ToString & "Bytes")
                End If
            Catch Ex As Exception
                MsgBox(Ex.ToString)
            End Try
        End If
    End Sub

    '******************************************
    '将字节数据传送出去
    '重载函数之一，需传入字符串
    '首先将字符串分解成数组，以便WriteFile函数可以使用
    '******************************************
    Public Sub Write(ByVal Buffer As String)
        Dim oEncoder As New System.Text.UTF8Encoding
        Dim aByte() As Byte = oEncoder.GetBytes(Buffer)
        Write(aByte) '调用另一个传输的重载函数
    End Sub

    '******************************************
    '将字节数据接收进来
    '重载函数之一，第一个参数是读取的字节数，第二个参数是返回的字节数组
    '如果传入的参数使用ByVal，原始的数据将不会被更改，故在此需用ByRef
    '在调用的地方才能得到此函数所在返回的结果
    '******************************************
    Public Sub Read(ByRef Bytes2Read As Integer, ByRef InputByte() As Byte)
        Dim iReadChars, iRc, lpErrors As Integer
        Dim mabtRxBuf As Byte()             '接收缓冲区
        '设置读取数据的长度
        If mhRS = -1 Then
            Throw New ApplicationException("尚未打开通信端口，不能读取数据!")
        Else
            '读取字节
            Try
                Dim cs As COMSTAT
                ClearCommError(mhRS, lpErrors, cs)  '取得缓冲区的字节数
                iReadChars = cs.cbInQue
                ReDim mabtRxBuf(iReadChars - 1)
                iRc = ReadFile(mhRS, mabtRxBuf, cs.cbInQue, iReadChars, 0)
                If iRc = 0 Then
                    '读取错误
                    Throw New ApplicationException("读取错误： " & iRc.ToString)
                Else
                    Bytes2Read = iReadChars
                    InputByte = mabtRxBuf
                End If
            Catch Ex As Exception
                '其他的读取错误状态
                Throw New ApplicationException("读取错误： " & Ex.Message, Ex)
            End Try
        End If
    End Sub

    '******************************************
    '将字符串数据接收进来
    '重载函数之一，第一个参数是读取的字节数，第二个参数是返回的字符串
    '如果传入的参数使用ByVal,原始的数据将不会被更改，故在此需用ByRef
    '在调用的地方才能得到此函数所返回的结果
    '******************************************
    Public Sub Read(ByRef Char2Read As Integer, ByRef InputString As String)
        Dim iReadChars, iRc, lpErrors As Integer
        Dim mabtRxBuf As Byte()   '接收缓冲区
        '设置读取数据的长度
        If mhRS = -1 Then
            Throw New ApplicationException("尚未打开通信端口，不能读取数据!")
        Else
            '读取字节
            Try
                Dim cs As COMSTAT
                ClearCommError(mhRS, lpErrors, cs)  '取得缓冲区内的字节数
                iReadChars = cs.cbInQue
                ReDim mabtRxBuf(iReadChars - 1)
                iRc = ReadFile(mhRS, mabtRxBuf, cs.cbInQue, iReadChars, Nothing)
                If iRc = 0 Then
                    '读取错误
                    Throw New ApplicationException("读取错误：" & iRc.ToString)
                Else
                    Char2Read = iReadChars
                    '转换字节数组为字符串
                    Dim oEncoder As New System.Text.UTF8Encoding
                    InputString = oEncoder.GetString(mabtRxBuf)
                End If
            Catch Ex As Exception
                '其他的读取错误状态
                Throw New ApplicationException("读取错误：" & Ex.Message, Ex)
            End Try
        End If
    End Sub

[sgmcumt]

请自行忽略代码中的<strong> </strong>，本来是想加粗显示，不知道为什么自动添加的<strong> </strong>

[水哥阿乐]

先把该教程示例的所有只读属性去掉再调试,如果出现问题,请贴出具体出错行代码,别来这整面的