BS EN 62056-47:2007 – Electricity metering — Data exchange for meter reading, tariff and load control — Part 47: COSEM transport layers for IPv4 networks

The Local_wPort, Remote_wPort, Local_UDP_Port, Remote_UDP_Port, Local_IP_Address and Remote_IP_Address parameters carry the same values as the corresponding UDP- DATA.request service being confirmed. The value of the Result parameter indicates whether the COSEM UDP-based transport layer was able to send the requested UDP Datagram (OK) or not (NOK). Use If implemented, this service primitive is used to confirm the result of a previous UDP- DATA.request service. It is locally generated and indicates only whether the Data in the .request primitive could be sent or not.
In other words, an UDP-DATA.confirm with Result == OK means only that the Data has been sent, and does not mean that the Data has been (or will be) successfully delivered to the destination.
5.3 Protocol specification for the COSEM UDP-based transport layer
5.3.1 General As it is shown on the left side of Figure 2, the COSEM UDP-based transport layer includes the Internet standard UDP layer, as specified in Internet standard STD0006, and the COSEM- specific light-weight wrapper sub-layer.
In this communication profile, the wrapper sub-layer is a state-less entity: its only roles are to ensure source and destination COSEM application process identification using the wPort numbers and to provide conversion between the OSI-style UDP-DATA.xxx service invoca- tions and the SEND() and RECEIVE() interface functions provided by the standard UDP. Although it is not necessary in the UDP-based profile, in order to have the wrapper protocol control information – in other words the wrapper header – the same in both COSEM transport layers, the wrapper sub-layer shall also include the Data Length information in the wrapper protocol data unit.
5.3.2 The wrapper protocol data unit (WPDU) The WPDU consists of two parts: • the wrapper header part, containing the wrapper protocol control information, and • the Data part, containing the DATA parameter – the COSEM APDU – of the corresponding UDP-DATA.xxx service invocation.
BS EN 62056-47:2007 – Electricity metering — Data exchange for meter reading, tariff and load control — Part 47: COSEM transport layers for IPv4 networks