Assistance Needed: GuruxDLMS Data Reception Issue After Moxa NPort Conversion

I’m currently working with an Itron SL7000 energy meter, which is connected to a Moxa NPort device via a serial COM port. The Moxa device converts the serial data to TCP and transmits it over port 4002 (IP: 10.100.121.101).

I’ve successfully tested the setup using the Ace Vision Web application, confirming that data is correctly transmitted from the source through the Moxa converter via HDLC tunneling over TCP. This indicates that the communication path from the energy meter to the Moxa device is      functioning properly.

However, I’m encountering an issue with the VB GuruxDLMS receiver. In the ReadDLMSPacket function, the line succeeded = Media.Receive(p) consistently returns False, preventing data reception.

Could provide guidance on resolving this GuruxDLMS receiver issue? Any suggestions on configuration adjustments or troubleshooting steps would be greatly appreciated.

Current Configuration:

Energy Meter: Itrong SL7000

Converter: Moxa NPort (Serial to TCP)

TCP Endpoint: 10.100.121.101:4002

Protocol: HDLC tunneling over TCP

 Public Sub Start()
        Dim media As IGXMedia = Nothing
        Dim comm As GXCommunicatation = Nothing
        Dim dlms As New GXDLMSSecureClient()
        Dim manufacturer As New GXManufacturer()

        Try
            manufacturer.Identification = "ACE"  ' Itron manufacturer ID  
            manufacturer.Name = "Itron"
            manufacturer.UseLogicalNameReferencing = True
            manufacturer.Standard = Standard.DLMS
            manufacturer.StartProtocol = StartProtocolType.IEC
            'manufacturer.Address = HDLCAddressType.Default

            '' Add authentication entry  
            manufacturer.Settings = New List(Of GXAuthentication)()
            manufacturer.Settings.Add(New GXAuthentication(Authentication.None, 17))

            '' Add server address settings (without HdlcAddressing)  
            manufacturer.ServerSettings = New List(Of GXServerAddress)()
            Dim serverAddress As New GXServerAddress()
            serverAddress.LogicalAddress = 1
            serverAddress.PhysicalAddress = 1
            manufacturer.ServerSettings.Add(serverAddress)

            ' Initialize TCP/IP connection to Moxa  
            media = New GXNet(NetworkType.Tcp, "10.100.121.101", 4002)
            media.Open()

            dlms.InterfaceType = InterfaceType.HDLC
            dlms.UseLogicalNameReferencing = True
            dlms.ClientAddress = 17
            dlms.ServerAddress = 1 'GXDLMSClient.GetServerAddress(1, 1)
            dlms.Authentication = Authentication.Low
            dlms.Password = System.Text.Encoding.ASCII.GetBytes("ABCDEFGH")

            '' Initialize communication  
            comm = New GXCommunicatation(dlms, media, False, Authentication.Low, "ABCDEFGH")
            comm.InitializeConnection(manufacturer)

            '' Read all available objects  
            ReadAllObjects(dlms, comm)

        Catch ex As Exception
            Console.WriteLine("Error: " & ex.Message)
        Finally
            If comm IsNot Nothing Then
                comm.Close()
            End If
        End Try
    End Sub

 Public Sub ReadDLMSPacket(data As Byte(), reply As GXReplyData)
       If data Is Nothing Then
           Return
       End If
       reply.[Error] = 0
       Dim eop As Object = If(Client.InterfaceType = InterfaceType.WRAPPER AndAlso TypeOf Media Is GXNet, Nothing, CByte(&H7E))
       Dim pos As Integer = 0
       Dim succeeded As Boolean = False
       Dim rd As New GXByteBuffer()
       Dim p As New ReceiveParameters(Of Byte())() With {
       .Eop = eop,
       .Count = Client.GetFrameSize(rd), ' Dynamic frame size  
       .AllData = True,
       .WaitTime = WaitTime
       }
       SyncLock Media.Synchronous
           While Not succeeded AndAlso pos <> 3
               WriteTrace("<- " + DateTime.Now.ToLongTimeString() + vbTab + GXCommon.ToHex(data, True))
               Media.Send(data, Nothing)
               succeeded = Media.Receive(p)
               If Not succeeded Then
                   If System.Threading.Interlocked.Increment(pos) >= 3 Then
                       Throw New Exception("Failed to receive reply from the device in given time.")
                   End If
                   If p.Eop Is Nothing Then p.Count = 1
                   Continue While
               End If
           End While
           rd = New GXByteBuffer(p.Reply)
           Try
               pos = 0
               'Loop until whole COSEM packet is received.
               While Not Client.GetData(rd, reply)
                   p.Reply = Nothing
                   If p.Eop Is Nothing Then
                       p.Count = Client.GetFrameSize(rd) ' Update frame size  
                   End If
                   While Not Media.Receive(p)
                       If System.Threading.Interlocked.Increment(pos) >= 3 Then
                           Throw New Exception("Failed to receive reply from the device in given time.")
                       End If
                   End While
               End While
           Catch ex As Exception
               WriteTrace("-> " + DateTime.Now.ToLongTimeString() + vbTab + GXCommon.ToHex(p.Reply, True))
               Throw ex
           End Try
       End SyncLock
       WriteTrace("-> " + DateTime.Now.ToLongTimeString() + vbTab + GXCommon.ToHex(p.Reply, True))
       If reply.[Error] <> 0 Then
           If reply.[Error] = CShort(ErrorCode.Rejected) Then
               Thread.Sleep(1000)
               ReadDLMSPacket(data, reply)
           Else
               Throw New GXDLMSException(reply.[Error])
           End If
       End If
   End Sub