Hi All,

I'm trying to setup an asynchronous client and I can send/receive one command and response, but when I try to send the second command, the command is sent (I verified by code inspection), but I am getting no response.

Im a begginner!

Heres the code, a majority of it is from the Microsoft example.

Option Explicit On
Imports System
Imports System.Net
Imports System.Net.Sockets
Imports System.Text
Imports system.convert
Imports System.Threading
Imports System.Collections
Imports System.ComponentModel

Public Class ComClient

Public Sub SendCommand(ByVal CommandString As String, ByRef ResponseString As String)

sendNetwork(CommandString)
sendDone.WaitOne()

tcpdataarival(ResponseString)
receiveDone.WaitOne()
End Sub


Public Sub sendNetwork(ByVal outstr As String)

frmMain.sender1.BeginSend(outstr, 0, outstr.Length, 0, New AsyncCallback(AddressOf SendCallback), frmMain.sender1)

End Sub


Public Sub tcpdataarival(ByRef responsestr As String)
Dim state As New StateObject
state.workSocket = frmMain.sender1
Dim responsebyte As String = ""

ReDim state.tcpBuffer(128)

frmMain.sender1.BeginReceive(state.tcpBuffer, 0, StateObject.tcpBufferSize, 0, New AsyncCallback(AddressOf ReceiveCallback), state)

responsestr = DecodeResponse(state.tcpBuffer)
End Sub


Public Sub tcpconnect()
Dim ipHostInfo As IPHostEntry = System.Net.Dns.GetHostEntry(frmMain.txtbIP.Text)
Dim ipAddress As IPAddress = ipHostInfo.AddressList(0)
Dim remoteEP As New IPEndPoint(ipAddress, 48362)

frmMain.sender1 = New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)
frmMain.sender1.BeginConnect(remoteEP, New AsyncCallback(AddressOf ConnectCallback), frmMain.sender1)


End Sub

Public Sub tcpdisconnect()
frmMain.sender1.Shutdown(SocketShutdown.Both)
frmMain.sender1.Close()

End Sub
Private Shared Sub ConnectCallback(ByVal ar As IAsyncResult)
Dim client As Socket = CType(ar.AsyncState, Socket)

' Complete the connection.
client.EndConnect(ar)

Console.WriteLine("Socket connected to {0}", client.RemoteEndPoint.ToString())

' Signal that the connection has been made.
connectDone.Set()
End Sub 'ConnectCallback
Private Shared Sub ReceiveCallback(ByVal ar As IAsyncResult)

' Retrieve the state object and the client socket
' from the asynchronous state object.
Dim state As StateObject = CType(ar.AsyncState, StateObject)
Dim client As Socket = state.workSocket

' Read data from the remote device.
Dim bytesRead As Integer = client.EndReceive(ar)

If bytesRead > 0 Then
' There might be more data, so store the data received so far.
state.sb.Append(Encoding.ASCII.GetString(state.tcp Buffer, 0, bytesRead))

' Get the rest of the data.
client.BeginReceive(state.tcpBuffer, 0, StateObject.tcpBufferSize, 0, New AsyncCallback(AddressOf ReceiveCallback), state)
Else
' All the data has arrived; put it in response.
If state.sb.Length > 1 Then
response = state.sb.ToString()
End If
' Signal that all bytes have been received.
receiveDone.Set()
End If
Console.WriteLine(receiveDone)
End Sub 'ReceiveCallback

Private Shared Sub SendCallback(ByVal ar As IAsyncResult)
' Retrieve the socket from the state object.
Dim client As Socket = CType(ar.AsyncState, Socket)

' Complete sending the data to the remote device.
Dim bytesSent As Integer = client.EndSend(ar)
Console.WriteLine("Sent {0} bytes to server.", bytesSent)

' Signal that all bytes have been sent.
sendDone.Set()
End Sub 'SendCallback

End Class 'ComClient

Public Class StateObject
' Client socket.
Public workSocket As Socket = Nothing
' Size of receive buffer.
Public Const tcpBufferSize As Integer = 128
' Receive buffer.
Public tcpBuffer(tcpBufferSize) As Byte
' Received data string.
Public sb As New StringBuilder
End Class 'StateObject