关于VB. net串口通信，小白求助

[sa220z]

我每次向设备发送一个命令，设备返回一个读数。我把这段代码放到一个timer里反复执行，每次在发送命令前和接受读数后，都清空了输入输出缓存区。
刚开始一切正常，但过一段时间，就无法接受到读数了，但是过了一两个小时重启程序就又正常了，请问哪位遇到过类似情况，是什么问题（软件或硬件）引发的，还是说初始化串口时要特殊设置一些参数？

[subzero]

不确认到底是上位机还是下位机哪里的问题，可以先找一个成熟的串口通信软件模拟你的定时操作，来判断到底是哪端的问题，再找解决方案。

[巴士上的邂逅]

读数在DataReceived事件里就行

[良朋]

建议你开一个多线程：

        Dim SerialComm = New Threading.Thread(New Threading.ThreadStart(AddressOf Sp_Receiving))
        SerialComm.Start()      '开线程

    Private Sub Sp_Receiving()
        Dim strIncoming As String
        Try
            If SerialPort1.BytesToRead > 0 Then
                strIncoming = SerialPort1.ReadExisting.ToString '读取缓冲区中的数据
                SerialPort1.DiscardInBuffer()

                'strIncoming = SerialPort1.ReadLine.ToString
                'SerialPort1.DiscardInBuffer()

                'ListBox1.Items.Add(Microsoft.VisualBasic.Left(strIncoming, InStr(strIncoming, vbCr) - 1))       '取到回车符位置数-1
                'ListBox1.Items.Add(Mid(strIncoming, 1, Len(strIncoming) - 1))       '长度-1
                ListBox1.Items.Add(strIncoming)

                ListBox1.SelectedIndex = ListBox1.Items.Count - 1
                If ListBox1.Items.Count > 1000 Then
                    Me.ListBox1.Items.Clear()
                End If

            End If
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
    End Sub

[清晨曦月]

就类似这样咯

   Private WithEvents mPort As SerialPort
    Event RequestData()
    Event Ready()
    Event Interrupt()
    Event RerequestData()

    Sub New(PortName As String, BaudRate As Integer)
        mPort = New SerialPort(PortName, BaudRate)
        Try
            mPort.Open()
        Catch ex As Exception
            MsgBox(ex.ToString)
        End Try
    End Sub

    Private Sub mPort_DataReceived(sender As Object, e As SerialDataReceivedEventArgs) Handles mPort.DataReceived
        Dim inData As String = CType(sender, SerialPort).ReadLine.TrimEnd({CChar(vbCr), CChar(vbLf)})
        If inData = (r_RequestData) Then
            RaiseEvent RequestData()
        ElseIf inData = (r_Ready) Then
            RaiseEvent Ready()
        ElseIf inData = (r_Interrupt) Then
            RaiseEvent Interrupt()
        ElseIf inData = r_RerequestData Then
            RaiseEvent RerequestData()
        ElseIf inData <> String.Empty Then
            Debug.Print("收到下位机的未知请求。[" & inData & "]")
        End If
    End Sub

    Private Sub mPort_Disposed(sender As Object, e As EventArgs) Handles mPort.Disposed
        Try
            If mPort IsNot Nothing AndAlso mPort.IsOpen Then
                Clear()
                mPort.Close()
            End If
        Catch ex As Exception
        End Try
    End Sub

    Protected Friend Sub Clear()
        Try
            mPort.BaseStream.Flush()
        Catch ex As Exception
        End Try
    End Sub