如何从vb.net的串行端口读取数据？

Question

I made a class and there is this sub named SendUSSD, when this is called it sends a ussd code like *123# to a COM port where a gsm mobile is connected. This ussd is supposed to return the mobile balance.

If IsOpen = True Then 'checks if the port is open
            SMSPort.WriteLine("AT+CUSD=1,""*123#""" vbCr) 'this sends the ussd code
            Form1.TextBox2.Text = SMSPort.ReadLine().ToString() 'this shows the response
End If

Now the problem is sometimes I get the full response like "Your current balance is so and so". But, most of the time I get a part of the message like "Your curr". My guess is that it takes some time to get the response, so how do I make this Form1.TextBox2.Text = SMSPort.ReadLine().ToString() line wait until the last character which is a full-stop to appear and then execute the line?

Answer 1

im using this class to connect com ports.

'connect like this
Public comm As New CommunicationManager
comm.Parity = "None"
    comm.StopBits = "One"
    comm.DataBits = "8"
    comm.BaudRate = "38400"
    comm.PortName = comport_ismi
    comm.OpenPort()

and the class

    Imports System.Text
    Imports System.Drawing
    Imports System.IO.Ports
    Imports System.Windows.Forms

Public Class CommunicationManager
#Region "Manager Enums"
    ''' <summary>
    ''' enumeration to hold our transmission types
    ''' </summary>
    Public Enum TransmissionType
        Text
        Hex
    End Enum

    ''' <summary>
    ''' enumeration to hold our message types
    ''' </summary>
    Public Enum MessageType
        Incoming
        Outgoing
        Normal
        Warning
        [Error]
    End Enum
#End Region

#Region "Manager Variables"
    'property variables
    Private _baudRate As String = String.Empty
    Private _parity As String = String.Empty
    Private _stopBits As String = String.Empty
    Private _dataBits As String = String.Empty
    Private _portName As String = String.Empty
    Private _transType As TransmissionType
    Private _displayWindow As RichTextBox
    'global manager variables
    Private MessageColor As Color() = {Color.Blue, Color.Green, Color.Black, Color.Orange, Color.Red}
    Private comPort As New SerialPort()
#End Region

#Region "Manager Properties"
    ''' <summary>
    ''' Property to hold the BaudRate
    ''' of our manager class
    ''' </summary>
    Public Property BaudRate() As String
        Get
            Return _baudRate
        End Get
        Set(value As String)
            _baudRate = value
        End Set
    End Property

    ''' <summary>
    ''' property to hold the Parity
    ''' of our manager class
    ''' </summary>
    Public Property Parity() As String
        Get
            Return _parity
        End Get
        Set(value As String)
            _parity = value
        End Set
    End Property

    ''' <summary>
    ''' property to hold the StopBits
    ''' of our manager class
    ''' </summary>
    Public Property StopBits() As String
        Get
            Return _stopBits
        End Get
        Set(value As String)
            _stopBits = value
        End Set
    End Property

    ''' <summary>
    ''' property to hold the DataBits
    ''' of our manager class
    ''' </summary>
    Public Property DataBits() As String
        Get
            Return _dataBits
        End Get
        Set(value As String)
            _dataBits = value
        End Set
    End Property

    ''' <summary>
    ''' property to hold the PortName
    ''' of our manager class
    ''' </summary>
    Public Property PortName() As String
        Get
            Return _portName
        End Get
        Set(value As String)
            _portName = value
        End Set
    End Property

    ''' <summary>
    ''' property to hold our TransmissionType
    ''' of our manager class
    ''' </summary>
    Public Property CurrentTransmissionType() As TransmissionType
        Get
            Return _transType
        End Get
        Set(value As TransmissionType)
            _transType = value
        End Set
    End Property

    ''' <summary>
    ''' property to hold our display window
    ''' value
    ''' </summary>
    Public Property DisplayWindow() As RichTextBox
        Get
            Return _displayWindow
        End Get
        Set(value As RichTextBox)
            _displayWindow = value
        End Set
    End Property
#End Region

#Region "Manager Constructors"
    ''' <summary>
    ''' Constructor to set the properties of our Manager Class
    ''' </summary>
    ''' <param name="baud">Desired BaudRate</param>
    ''' <param name="par">Desired Parity</param>
    ''' <param name="sBits">Desired StopBits</param>
    ''' <param name="dBits">Desired DataBits</param>
    ''' <param name="name">Desired PortName</param>
    Public Sub New(baud As String, par As String, sBits As String, dBits As String, name As String, rtb As RichTextBox)
        _baudRate = baud
        _parity = par
        _stopBits = sBits
        _dataBits = dBits
        _portName = name
        _displayWindow = rtb
        'now add an event handler
        AddHandler comPort.DataReceived, New SerialDataReceivedEventHandler(AddressOf comPort_DataReceived)
    End Sub

    ''' <summary>
    ''' Comstructor to set the properties of our
    ''' serial port communicator to nothing
    ''' </summary>
    Public Sub New()
        _baudRate = String.Empty
        _parity = String.Empty
        _stopBits = String.Empty
        _dataBits = String.Empty
        _portName = comport_ismi
        _displayWindow = Nothing
        'add event handler
        AddHandler comPort.DataReceived, New SerialDataReceivedEventHandler(AddressOf comPort_DataReceived)
    End Sub
#End Region

#Region "WriteData"
    Public Sub WriteData(msg As String)
        Select Case CurrentTransmissionType
            Case TransmissionType.Text
                'first make sure the port is open
                'if its not open then open it
                If Not (comPort.IsOpen = True) Then
                    comPort.Open()
                End If
                'send the message to the port
                comPort.Write(msg)
                'display the message
                DisplayData(MessageType.Outgoing, msg & Convert.ToString(vbLf))
                Exit Select
            Case TransmissionType.Hex
                Try
                    'convert the message to byte array
                    Dim newMsg As Byte() = HexToByte(msg)
                    'send the message to the port
                    comPort.Write(newMsg, 0, newMsg.Length)
                    'convert back to hex and display
                    DisplayData(MessageType.Outgoing, ByteToHex(newMsg) & Convert.ToString(vbLf))
                Catch ex As FormatException
                    'display error message
                    DisplayData(MessageType.[Error], ex.Message)
                Finally
                    _displayWindow.SelectAll()
                End Try
                Exit Select
            Case Else
                'first make sure the port is open
                'if its not open then open it
                If Not (comPort.IsOpen = True) Then
                    comPort.Open()
                End If
                'send the message to the port
                comPort.Write(msg)
                'display the message
                DisplayData(MessageType.Outgoing, msg & Convert.ToString(vbLf))
                Exit Select
        End Select
    End Sub
#End Region

#Region "HexToByte"
    ''' <summary>
    ''' method to convert hex string into a byte array
    ''' </summary>
    ''' <param name="msg">string to convert</param>
    ''' <returns>a byte array</returns>
    Private Function HexToByte(msg As String) As Byte()
        'remove any spaces from the string
        msg = msg.Replace(" ", "")
        'create a byte array the length of the
        'divided by 2 (Hex is 2 characters in length)
        Dim comBuffer As Byte() = New Byte(msg.Length / 2 - 1) {}
        'loop through the length of the provided string
        For i As Integer = 0 To msg.Length - 1 Step 2
            'convert each set of 2 characters to a byte
            'and add to the array
            comBuffer(i / 2) = CByte(Convert.ToByte(msg.Substring(i, 2), 16))
        Next
        'return the array
        Return comBuffer
    End Function
#End Region

#Region "ByteToHex"
    ''' <summary>
    ''' method to convert a byte array into a hex string
    ''' </summary>
    ''' <param name="comByte">byte array to convert</param>
    ''' <returns>a hex string</returns>
    Private Function ByteToHex(comByte As Byte()) As String
        'create a new StringBuilder object
        Dim builder As New StringBuilder(comByte.Length * 3)
        'loop through each byte in the array
        For Each data As Byte In comByte
            'convert the byte to a string and add to the stringbuilder
            builder.Append(Convert.ToString(data, 16).PadLeft(2, "0"c).PadRight(3, " "c))
        Next
        'return the converted value
        Return builder.ToString().ToUpper()
    End Function
#End Region

#Region "DisplayData"
    ''' <summary>
    ''' method to display the data to & from the port
    ''' on the screen
    ''' </summary>
    ''' <param name="type">MessageType of the message</param>
    ''' <param name="msg">Message to display</param>
    <STAThread> _
    Private Sub DisplayData(type As MessageType, msg As String)
        '_displayWindow.Invoke(New EventHandler(Sub()
        '                                           _displayWindow.SelectedText = String.Empty
        '                                           _displayWindow.SelectionFont = New Font(_displayWindow.SelectionFont, FontStyle.Bold)
        '                                           _displayWindow.SelectionColor = MessageColor(CInt(type))
        '                                           _displayWindow.AppendText(msg)
        '                                           _displayWindow.ScrollToCaret()

        '                                       End Sub))
    End Sub
#End Region

#Region "OpenPort"
    Public Function OpenPort() As Boolean
        Try
            'first check if the port is already open
            'if its open then close it
            If comPort.IsOpen = True Then
                comPort.Close()
            End If

            'set the properties of our SerialPort Object
            comPort.BaudRate = Integer.Parse(_baudRate)
            'BaudRate
            comPort.DataBits = Integer.Parse(_dataBits)
            'DataBits
            comPort.StopBits = DirectCast([Enum].Parse(GetType(StopBits), _stopBits), StopBits)
            'StopBits
            comPort.Parity = DirectCast([Enum].Parse(GetType(Parity), _parity), Parity)
            'Parity
            comPort.PortName = _portName
            'PortName
            'now open the port
            comPort.Open()
            'display message
            DisplayData(MessageType.Normal, "Port AÇILDI: " + DateTime.Now + vbLf)
            'return true
            Return True
        Catch ex As Exception
            DisplayData(MessageType.[Error], ex.Message)
            Return False
        End Try
    End Function
#End Region

#Region "ClosePort"

    Public Function ClosePort() As Boolean
        Try
            'first check if the port is already open
            'if its open then close it
            If comPort.IsOpen = True Then
                comPort.Close()
            End If
            'display message
            DisplayData(MessageType.Normal, "Port KAPANDI: " + DateTime.Now + vbLf)
            'return true if port is closed
            If comPort.IsOpen = False Then
                Return True
            End If
            DisplayData(MessageType.Normal, "Kapatmada hata oluştu" & vbLf)
            Return False
        Catch ex As Exception
            DisplayData(MessageType.[Error], ex.Message)
            Return False
        End Try
    End Function

#End Region

#Region "SetParityValues"
    Public Sub SetParityValues(obj As Object)
        For Each str As String In [Enum].GetNames(GetType(Parity))
            DirectCast(obj, ComboBox).Items.Add(str)
        Next
    End Sub
#End Region

#Region "SetStopBitValues"
    Public Sub SetStopBitValues(obj As Object)
        For Each str As String In [Enum].GetNames(GetType(StopBits))
            DirectCast(obj, ComboBox).Items.Add(str)
        Next
    End Sub
#End Region

#Region "SetPortNameValues"
    Public Sub SetPortNameValues(obj As Object)

        For Each str As String In SerialPort.GetPortNames()
            DirectCast(obj, ComboBox).Items.Add(str)
        Next
    End Sub
#End Region

#Region "comPort_DataReceived"
    ''' <summary>
    ''' method that will be called when theres data waiting in the buffer
    ''' </summary>
    ''' <param name="sender"></param>
    ''' <param name="e"></param>
    Private Sub comPort_DataReceived(sender As Object, e As SerialDataReceivedEventArgs)
        'determine the mode the user selected (binary/string)
        Select Case CurrentTransmissionType
            'user chose string
            Case TransmissionType.Text
                'read data waiting in the buffer
                Dim msg As String = comPort.ReadExisting()
                'display the data to the user
                DisplayData(MessageType.Incoming, msg)
                ' + "\n");  **************
                Exit Select
                'user chose binary
            Case TransmissionType.Hex
                'retrieve number of bytes in the buffer
                Dim bytes As Integer = comPort.BytesToRead
                'create a byte array to hold the awaiting data
                Dim comBuffer As Byte() = New Byte(bytes - 1) {}
                'read the data and store it
                comPort.Read(comBuffer, 0, bytes)
                'display the data to the user
                DisplayData(MessageType.Incoming, ByteToHex(comBuffer))
                ' + "\n");
                Exit Select
            Case Else
                'read data waiting in the buffer
                Dim str As String = comPort.ReadExisting()
                'display the data to the user
                DisplayData(MessageType.Incoming, str)
                ' + "\n");
                Exit Select
        End Select
    End Sub
#End Region
End Class

Answer 2

I guess you are using the DataReceived event, if so, you can just take the data and split it by the lastIndexOf(Enviroment.NewLine). you will have two part the first one is a string with some amount of lines and the second one is a string that contain no more lines. You can take the first part and split it by new line and even create a new event (LineReceived). for the second part(the part after the lastIndexOf(Enviroment.NewLine)) of the data just concatenate it to the beginning of the data that will arrive the next time.

Answer 3

Try setting comm.Newline . Probably should be vbCR.