How is DLMS/COSEM different from other standards
How is DLMS/COSEM different from other standards for meter data exchange?
The most commonly used standard for meter data exchange is the FLAG protocol, standardised for the purposes of electricity metering as IEC 61107 by IEC TC 13. Other protocols widely used are:
- the Euridis protocol used mainly in France over twisted pairs, standardised by IEC TC 13 as IEC 62056-31:1999 for electricity metering;
- MBUS for heat metering, standardised by CEN TC 294 as EN1434-3:1997 (future EN 13757-2 and -3),
- IEC 60870-5-102:1996 for transmission of integrated totals, in and between transmission and distribution stations, standardised by IEC TC 57;
- in North America, the ANSI C12.18 (optical port), C12.19 (utility tables) and C12.21 (communication through telephone modems).
While it is not the objective here to give a detailed comparison between these protocols, the main points, rendering DLM/COSEM particularly suitable to meet the needs of the liberalised energy markets are summarised below:
- DLMS/COSEM defines an interface model, valid for all kind of energy types, like electricity, gas, water, heat etc. Each interface object has a unique standard identifier, identifying the data on the display and over the communication line. This model is completely independent from the protocol layers used for transporting the data. It supports innovation and future evolution by allowing manufacturer specific instances, attributes, methods, and the possibility to add new interface classes and versions without changing the services to access the objects, thus maintaining interoperability.
- The interface class definitions standardise a number of widely used meter functionality, like demand registration, tariff and activity scheduling, handling time synchronisation and power failures, power quality metering to name just a few. Unambiguous interpretation of data is ensured by defining the data types to be used for the attributes, and/or by requiring to send this type information with the data.
- DLMS/COSEM provides controlled and secure access by various parties acting on the liberalised energy markets to selected portions of the information available in the metering equipment.
- As the interface model is completely independent from the communication media, a wide choice of media can be used, without ever changing the model and the data management application of the data collecting system. While today serial interfaces are supported, using DLMS/COSEM over the Internet is already planned.
- Unlike with older protocols, where - for example in the case of using IEC 61107 - a specific device driver in the data collection system was necessary for every new metering equipment, DLMS/COSEM facilitates to build generic drivers, able to communicate various meter types from different manufacturers.
- DLMS/COSEM has been selected by both the electricity and the water/gas/heat metering community as the standard of choice, which is particularly favourable for multi-energy providers gaining ground.
This unique combination of features, not available in any other metering protocols known presently, supports the business processes of the various stakeholders on the liberalised markets, support innovation and competition, and drastically reduce system life cycle costs.