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DLMS/COSEM Overview
DLMS User association have extended the IEC 61334-4-41 Application layer to give a business domain oriented interface object model for metering devices and defined communication profiles based on popular OSI model. Interface object model augers well for the Smart Grid initiatives across the world – from Demand response to Peak Load Management, to real-time information availability, data security and support for all energy types including electricity, gas etc. DLMS User association keeps up their continued effort in strengthening the protocol by filling the gaps and amending specification to cater to new technologies and market requirements.
IEC62056-62: Interface Classes – This specification defines the standard Interface Classes which can be used to represent all possible kinds of Meter Data. Using this specification meter data is abstracted into High-level objects, which can then be operated upon by the protocol stack.
IEC62056-61: OBIS - OBject Identification System defines a standard list of Meter data object identifiers in the form of a 6 character code for each object. This list is maintained by the DLMS-UA.
IEC62056-53: COSEM Application Layer- COSEM (Companion Specification for Energy Metering) defines an Application Layer protocol that can handle Meter data and perform the basic functions of data set/get/action operations in the Meter. In addition to these, COSEM handles access rights, client-server connection handling, abstracting meter data from/to COSEM class instances, framing data into COSEM packets, high-level segmentation of data into blocks etc.
IEC62056-46: HDLC Datalink Layer-HDLC defines a standard Datalink layer performing the functions of low-level addressing, data integrity checks, data sequencing, segmentation and assimilation, link-level handshaking, data-flow control etc. The Datalink layer’s main function is to reliably transport COSEM data packets between the client and the server.
IEC62056-47: COSEM Transport layer for Ipv4 networks.
IEC62056-42: Physical Layer- This standard specifies the physical layer services for data communication.
IEC62056-21: Direct Local Data Exchange- Alternate ASCII-based protocol stack. A new mode (MODE E) in this specification allows the client to negotiate a switchover to COSEM/HDLC(62056-53&46) following which all communication will use the COSEM/HDLC protocol stack.
• Covers all metering functions required on the liberalized market. The functions are modeled using metering domain specific interface objects. This allows developing meters meeting exact customer needs, using standard building blocks. It also allows innovation and competition by enhancing functionality in a standard way as required while maintaining interoperability.
• Ensures unique identification of all metering equipment world-wide and unambiguous identification of all data elements.
• Ensures unambiguous interpretation of all metering data.
• Allows controlled and selective access by various parties to application relevant data.
• Improves efficiency through effective data organization and encoding.
• Provides various levels of security mechanisms to control access to data depending on authentication and access rights.
• Covers all type of metering equipment, including electricity, gas, water, heat etc.
• Is suitable from the simplest devices to the most complex ones.
• Opens the way for exchanging data over various communication media, as the meter data model is independent of the communication protocol stack.
• Brings interoperability, and therefore lowers costs, as it is based on a standard data model and internationally approved standard protocols.
• Provides mechanisms to facilitate installation, as the data collection system is able to learn the data structure of the newly installed meter and to download the parameters as required by the application and metering site.
• Allows developing a genuine driver, as the meter describes the functions available and sends all information necessary to interpret data. This allows meter manufacturers and data collection system providers to concentrate on the applications relevant for their customers rather than on connectivity and interfaces; comes complete with a conformance testing scheme to guarantee interoperability.Â
• DLMS/COSEM is open
• Energy type, manufacturer and communication media independent interface model
• DLMS/COSEM supports all energy types.
• The COSEM model supports any device complexity
• All data can be unambiguously identified
• Clear and unambiguous data interpretation
• DLMS/COSEM supports innovation and competition
• Support of various communication architectures and protocols
• Efficient, secure, controlled and selective data access
• Safe data transport via leased lines, PSTN, GSM
• Meter data exchange via the internet
• Low protocol overhead and efficient encoding
• System integration, meter installation and maintenance facilitated
• DLMS/COSEM is self-descriptive allowing to develop generic drivers
• Cost reduction through interoperability
• Conformance testing
