DLMS News - IEC standards on the go




As explained in earlier issues of Metering International, the DLMS User Association defined its findings in ‘coloured books’ which form technical reports on COSEM, the companion specification for energy metering. The Orange Book handles the description of the object identification system OBIS. Both general purpose objects (eg ‘energy register’ or ‘number of days since last reset’) and abstract objects (eg of class ‘association’) are described.

The structured description of application items translates to a number, which is nothing else but the object name, applied to an object of the Blue Book. This book contains exact descriptions of the functionality of meters, whether they are complex meters for commercial and industrial use or simpler meters for residential use. These descriptions are called ‘Interface Objects’.


The members of the DLMS User Association have initiated activities in standardisation bodies, this time in IEC TC13, the Technical Committee which establishes standards for ‘equipment for electrical energy measurement and load control’ – for example energy meters. Its Working Group 14, handling ‘data exchange for meter reading, tariff and load control’, reached a milestone in its work programme, as it sent the documents ‘Interface Objects’ and ‘OBIS Object Identification System’ to IEC headquarters in Geneva. This puts these documents on the table of national IEC committees world-wide.

These committees will have to vote on the documents, which are called CDVs. If there is a positive vote, the document will be published as FDIS (Final Draft Inter-national Standard) in the second half of this year. These documents will then help to build up the library of DLMS-oriented standards. Let us remember that the first DLMS standard (IEC 61334-4-41) was released in 1996 by IEC TC57, which establishes standards for power system control and associated communications.

While the voting period goes on there will be no standstill in the DLMS UA and in IEC TC13 WG14. The channel-oriented documents will also reach CDV stage, which means that the Physical Layer, the Data Link Layer and the Application layer will also be defined. They will carry the interface objects described above and allow a system to be built up which is able to cope with the challenges of the liberalised market and the requirements for energy trading.