Timer in loop

[Pteranodon]

As per the code below, this app sends a message via TCP sockets and waits for a reply. It should timeout after 3 seconds (the interval set for tmrSend) or after the reply arrives.

The problem is that tmrSend.Start does not seem to be doing anything. The executing thread is tied up in this loop, and it becomes and endless loop if an acknowledgement is not sent, because the bElapsed variable is never set to true since the tmrSend_Tick event does not fire.

   
  Private Sub tmrSend_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles tmrSend.Tick
        bElapsed = True
    End Sub

Private Sub SendData(sMsg as string)  
                     
Try

    Dim tcp As New TcpClient

    TCP.Connect(curLab.IPAddress, curLab.IPPort)

    TCP.NoDelay = True

    Dim stream As NetworkStream = TCP.GetStream()

    Dim data As [Byte]()
    'Convert sMsg to byte array Data to send to stream
    data = StrToByteArray(sMsg)

    stream.Write(data, 0, data.Length)

    Thread.Sleep(0)

    If curLab.WaitforACKnowledgement Then

         tmrSend.Enabled = True

         tmrSend.Start()

         bElapsed = False

         sReply = ""

         Do While bElapsed = False Or stream.DataAvailable = True

               If bElapsed Then Exit Do

               If stream.DataAvailable Then

                      Dim lenReply As Integer, iOffset As Integer, iSize As Integer

                      iSize = 1024

                      Dim strReply(iSize) As Byte

                      lenReply = 1

                      Do Until lenReply = 0
                              lenReply = stream.Read(strReply, iOffset, iSize)
                              sReply = sReply & ByteArrayToString(strReply)
                              If lenReply > iSize Then
                                        iOffset = iOffset + lenReply
                              Else
                                        Exit Do
                              End If
                      Loop

            stream.Close()

             Exit Do

          End If

          Thread.Sleep(0)

       Loop

    End If

tmrSend.Stop()

stream.Close(500)

tcp.Close()

bDataSent = True
end sub