03-1 (Chinese edition) Meter Data Exchange
Conformance Testing
Meter Data Exchange using named and standardized objects
The standardized DLMS/COSEM framework for meter data exchange
With international standardization in the IEC and conformance testing achieved, the DLMS User Association is proud to announce the achievement of it's aims as declared at its foundation in 1997. The association, whose members are the leading players in the energy industry, utilities, metering equipment manufacturers and system providers, also provides the conformance testing process and the maintenance of the specification. A framework is completed; all elements are defined in standards (IEC 62056 series) and in the so-called coloured books. The coloured books are maintained regularly and contain the latest up-to-date information. Corrections and amendments to the coloured books will be transferred to international standards according to their maintenance schedule.
The Green Book (Three Layer Connection Oriented Architecture) holds the parts "direct local data exchange", "physical layer services and procedures for connection oriented asynchronous data exchange", "data link layer using HDLC protocol" and "COSEM application layer". It describes a three-layer protocol stack, based on the ISO/OSI model, to transport data to and from the meter using the COSEM model described in the Blue Book. Interoperability is ensured through the possibility of negotiating features and parameters of each layer. The protocol stack provides a few standardized services to access the COSEM objects. In fact, any protocol stack, able to provide this standardized service set can carry the COSEM model.
The Blue Book (Identification System and Interface Classes) handles the naming system OBIS (object identification system) and the interface objects. It describes an energy type, vendor- and communication media independent model of the metering equipment. The COSEM model, based on a state-of-the-art object oriented approach, working with objects close to the metering domain (like registers, profiles, clock, schedules, communication setup and so forth), provides a standardized view of the data generated, stored, displayed on and transmitted from the meter.
The OBIS system provides a solution for identifying all metering data in a standardized way. Through standardized ways to add new interface classes and instances, the model supports innovation and competition while maintaining interoperability. In the next step existing draft standards for heat, gas and water meters will be incorporated.
The Yellow Book (Conformance Test Process) describes the conformance testing process, including the test plans, the test tool and the certification process.
The DLMS/COSEM specification, which brings a new level of data security through access control and enhanced authentication mechanisms, puts a special emphasis on interoperability through the standardized meter model and the negotiable protocol features. It comes complete with a conformance test tool, thus offering a greatly simplified system integration and reducing costs.
The next focus of the DLMS User Association is moving COSEM to the information highway, the Internet. The COSEM framework allows transporting the COSEM meter model described with the COSEM interface objects, through the communication media independent COSEM Application layer and the media dependent lower protocol layers. It is relatively straightforward to use the TCP-UDP/IP layers residing over lower data link and physical layers instead of the data link layer and physical layers currently defined in the "Green Book". The addressing provided by the HDLC layer can be mapped to IP addresses for the physical devices and TCP-UDP port numbers for the logical devices and application associations. The existing Application layer protocol data units, carrying the DLMS/COSEM services can then be easily transported as TCP or UDP datagrams. In this way, the COSEM applications can easily live together with other Internet applications.