.NET (Core and Framework)

Private Sub ReceiveMessages()
        Try
            Dim receiveBytes As [Byte]() = TCudpClient.Receive(RecEndpoint)
        ' Some error checking code omitted
            Process_Heartbeat(receiveBytes)

            If NewSettings Then ' There are some queued commands
                UpDating = True ' Set a flag to prevent new commands being added while we are processing existing ones
                Send_Commands() ' See below
                UpDating = False
                NewSettings = False
            End If
            ThreadReceive = New System.Threading.Thread(AddressOf ReceiveMessages)
            ThreadReceive.Start()
        Catch ex As System.Threading.ThreadAbortException
            ' this generally means that the thread was deliberately aborted, so we can ignore it
        Catch e As Exception
            If Not ShuttingDown Then Throw New ApplicationException("Problem receiving data from Thermostat" & vbCrLf, e)
        End Try
    End Sub

    Private Sub Send_Commands()
        Static blInitDone As Boolean
        If Not blInitDone Then
            TCudpClient.Connect(IPAddress.Parse(IPText), COMMANDPORT) ' presumably only need to do this once
            'It appears that the first message sent after the Connect command sometimes fails to be transmitted,
            'so we make sure that it gets sent twice
            For Each tc In ThermostatCommands ' find the first available command
               If tc.Pending Then
                    Application.DoEvents()
                    System.Threading.Thread.Sleep(100)
                    SendMessage(tc.ComBuff) ' See below
                    Exit For
                End If
            Next
            blInitDone = True
        Else
        End If

        For Each tc In ThermostatCommands
            If tc.Pending Then
                Application.DoEvents()
                System.Threading.Thread.Sleep(100)
                SendMessage(tc.ComBuff) ' See below
                tc.ComBuff = Nothing
                tc.Pending = False
            End If
        Next
    End Sub

    Private Sub SendMessage(ByVal bytArray() As Byte)
        Dim intReturn As Integer
        intReturn = TCudpClient.Send(bytArray, bytArray.Length)
        If intReturn <> bytArray.Length Then
            Throw New ApplicationException("Problem sending command to Thermostat")
        End If
    End Sub