仅在从vb.net中的以太网设备接收数据时启动功能

Question

我正在编写一个vb.net应用程序，用于从以太网设备接收数据并将该数据存储在文本文件中。有没有办法只在从设备发送数据时才启动函数？

例如，

Public Sub Main()
      'This should run only when data is received from the device
end sub

这是我的代码：

Imports System
Imports System.Net
Imports System.Net.Sockets
Imports System.Text
Imports System.IO

Public Class Form1
'Data buffer for incoming data.
Dim bytes(1024) As Byte
Dim remoteEP As New IPEndPoint(IPAddress.Parse("169.254.244.11"), 10051)

'Create a TCP/IP socket.
Dim sender As New Socket(AddressFamily.InterNetwork, _
    SocketType.Stream, ProtocolType.Tcp)
Public Sub Main()
    'Connect the socket to the remote endpoint.
    sender.Connect(remoteEP)

    Dim bytesRec2, time_date

    time_date = Date.Now.ToString("dd-MM-yyyy-hh-mm-ss")

    Dim filepath As String = "hexfiles/" & time_date + ".hex"


    If Not System.IO.File.Exists(filepath) Then
        System.IO.File.Create(filepath).Dispose()
    End If

    Dim text_data

    While (True)

        bytesRec2 = sender.Receive(bytes)

        text_data = System.Text.Encoding.ASCII.GetString(bytes, 0, bytesRec2)

        ByteArrayToFile(filepath, GetByteArray(bytes, 0, bytesRec2))

        If text_data.IndexOf("CALL END") >= 0 Then

            Dim newFilePath As String = filepath.Replace(".hex", ".mp3")

            System.IO.File.Move(filepath, newFilePath)
            sender.Disconnect(1)
            Exit Sub
        End If
    End While

End Sub

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

Private Function GetFileContents(ByVal file_name As String) As String
    Dim stream_reader As New IO.StreamReader(file_name)
    Dim txt As String = stream_reader.ReadToEnd()
    stream_reader.Close()
    Return txt
End Function

Private Function GetByteArray(ByVal MyArray As System.Array, ByVal Start As Integer, ByVal Length As Integer) As Byte()
    Dim ReturnValue(Length - 1) As Byte
    Array.ConstrainedCopy(MyArray, Start, ReturnValue, 0, Length)
    Return ReturnValue
End Function

Public Function ByteArrayToFile(ByVal _FileName As String, ByVal _ByteArray() As Byte) As Boolean

    Try
        ' Open file for reading
        Dim _FileStream As New System.IO.FileStream(_FileName, System.IO.FileMode.Append, System.IO.FileAccess.Write)

        ' Writes a block of bytes to this stream using data from a byte array.
        _FileStream.Write(_ByteArray, 0, _ByteArray.Length)

        ' close file stream
        _FileStream.Close()

        Return True
    Catch _Exception As Exception
        ' Error
        Console.WriteLine("Exception caught in process: {0}", _Exception.ToString())
    End Try
End Function
End Class