Receive socket with connection left open

[trussell]

I'm working on an application in VB2010 Express. This application is a tcp connection between a PC and a remote IP device, displaying the data from the remote device's data packets in a text box.

My initial attempt is in the code snippet below, and it works - but... The remote device connection is through a network that has, between two routers, a 9600 baud modem phone line connection. Because of this very slow connection I need to reduce as much as possible the "extraneous " data packets. The way I want to do this is to initially make a network connection to the remote device, then leave the connection in place while the PC application is running, dropping the connection once the application is closed. This will remove the "extra" connect and dis-connect data packets sent over the network.

I've tried commenting out the "socket1.Close( )" command but then only the first received data packet from the remote device is displayed in the text box. All subsequent data packets are not displayed, even though I can see that they are being sent from the remote device to the PC via Wireshark.

Any help or pointing in the right direction would be appreciated.

Dim tcplistener_remote As New TcpListener(IPAddress.Any, ip_port_remote)

Dim Main_Timer As Int16 = 10		' 10 milli-seconds
Dim Keep_Alive_Timer As Int32 = 5000	' keep alive timer set to 5 seconds

Dim counter As Int32 = 0


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

	tcplistener_remote.Start()

	Timer1.Interval = Main_Timer		' set the main timer interval
	Timer1.Enabled = True			' start the timer

	Timer2.Interval = Keep_Alive_Timer		' set up the timer
	Timer2.Enabled = True			' and start the timer

End Sub		 ' end of Form1_Load


Public Sub ListenToEthernet()
	If tcplistener_remote.Pending = True Then			 	' Check to see if there is data coming from a remote site

		Dim socket1 = tcplistener_remote.AcceptSocket()		' set up a socket called 'socket1'

		Dim k_val As Integer = 0
		Dim num_bytes(socket1.ReceiveBufferSize) As Byte	' obtain the number of bytes in the incoming socket and then
		'								move that number of bytes over to the array 'num_bytes'

		Try
			k_val = socket1.Receive(num_bytes)

			Catch se As Exception
				' if there is an exception do something
			Exit Try
		End Try

		Dim returndata As String
		returndata = Encoding.ASCII.GetString(num_bytes)

		Dim array1(90) As Char
		array1 = returndata.ToCharArray()

		TextBox1.Text = array1

		socket1.Close()	' close the socket!!!

	End If

End Sub	' end of ListenToEthernet