vb2005串口通讯

shingyuan 2009-01-25 08:37:03

Public Class Form1

我些一个串口通讯的程序，用的是VB.net2005.用的是SerialPort类来实现。目的是通过调制解调器拨号，然后通过交换机连接到单片机（本程序单片机的号码是“#2”）。然后向单片机发送握手信号“OXEB”，然后等待单片机回复握手信号。捕捉并识别单片机回发的握手信号“OXEB”然后就OK了。我的问题是：我可以用这个方法打通电话（如果终端接的不是单片机，而是电话的话）。但如果接单片机就没反应了。不晓得问题出在了哪里？请各位帮我一下。
Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim text As String

Using com3 As IO.Ports.SerialPort = _
My.Computer.Ports.OpenSerialPort("COM3", 9600)
com3.DtrEnable = True
com3.Write("ATD #2" & vbCrLf)
' Insert code to transfer data to and from the modem.

com3.Write("OXEB")
com3.Close()
text = ReceiveSerialData()
com3.Close()
MessageBox.Show("text")

End Using

End Sub

Public Function ReceiveSerialData() As String
' Receive strings from a serial port.
Dim returnStr As String = ""

Using com3 As IO.Ports.SerialPort = _
My.Computer.Ports.OpenSerialPort("COM3", 9600)
Do
Dim Incoming As String = com3.ReadLine()
If Incoming Is Nothing Then
Exit Do
Else
returnStr &= Incoming & vbCrLf
End If
Loop
End Using

Return returnStr
End Function

End Class

...全文

540 1 打赏收藏转发到动态举报

写回复

用AI写文章

1 条回复

切换为时间正序

请发表友善的回复…

发表回复

zdingyun 2009-01-25

打赏
举报

LZ:你上下位机通信协议未叙述清楚.我认为你所需发送的0XEB实际是&HEB字节数据,不是4字节的ASCII字符.



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

        Dim bytHex(0) As Byte

        bytHex(0) = &HEB

        SerialPort1.Write(bytHex, 0, bytHex.Length)

    End Sub

下面提供基于字节数据收发的VB.NET代码:

Public Class Form1

    Dim mSTR As String

    Dim strData As String

    Dim strDat As String

    'Dim mSize1 As Integer

    Dim mRecvByte() As Byte

    Dim Hexsj As String

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

        Dim mSize As Integer = Me.SerialPort1.BytesToRead

        'mSize1 = mSize

        ReDim mRecvByte(mSize - 1)

        SerialPort1.Read(mRecvByte, 0, mSize)

        'mSTR = Encoding.Default.GetString(mRecvByte, 0, mSize)

        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) '委托

        'TextBox4.Text = mSTR

        Dim i As Integer

        For i = 0 To UBound(mRecvByte) 'mSize - 1

            strData = strData & IIf(mRecvByte(i) > 15, Hex(mRecvByte(i)), "0" & Hex(mRecvByte(i)))

        Next

        Dim sj As Byte

        For i = 1 To Len(strData) Step 2 '处理为ASCII字符

            sj = Val("&H" & Mid(strData, i, 2))

            If sj < 32 Or sj > 128 Then '当接收字节中有Chr(0)时，其后字符被切割

                strDat = strDat & "."

            Else

                strDat = strDat & Chr(sj)

            End If

        Next

        TextBox1.Text = strDat '显示字符

        TextBox2.Text = strData '显示为进制

        TextBox3.Text = Len(strData) / 2

    End Sub



    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

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

        SerialPort1.ReceivedBytesThreshold = 1

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

        Hexsj = "002702013524200239892700020020010201E9030D07"

        TxtSend.Text = Hexsj

    End Sub



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

        strData = ""

        strDat = ""

        TextBox1.Text = ""

        TextBox2.Text = ""

        TextBox3.Text = ""

    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

        Dim bytHex() As Byte

        ReDim bytHex((Len(Hexsj) \ 2) - 1)

        Dim i As Integer

        For i = 1 To Len(Hexsj) Step 2

            bytHex((i - 1) / 2) = Val("&H" & Mid(Hexsj, i, 2))

        Next

        SerialPort1.Write(bytHex, 0, bytHex.Length)

    End Sub

End Class