IEC 62056

IEC 62056 is a set of standards for Electricity metering data exchange by International Electrotechnical Commission. The IEC 62056 standards are the International Standard versions of the DLMS/COSEM specification. DLMS or Device Language Message Specification (originally Distribution Line Message Specification), is the suite of standards developed and maintained by the DLMS User Association and has been adopted by the IEC TC13 WG14 into the IEC 62056 series of standards. The DLMS User Association maintains a D Type liaison with IEC TC13 WG14 responsible for international standards for meter data exchange and establishing the IEC 62056 series. In this role, the DLMS UA provides maintenance, registration and compliance certification services for IEC 62056 DLMS/COSEM.

COSEM or Companion Specification for Energy Metering, includes a set of specifications that defines the Transport and Application Layers of the DLMS protocol. The DLMS User Association defines the protocols into a set of four specification documents namely Green Book, Yellow Book, Blue Book and White Book. The Blue book describes the COSEM meter object model and the OBIS object identification system, the Green book describes the Architecture and Protocols, the Yellow book treats all the questions concerning conformance testing, the White book contains the glossary of terms. If a product passes the Conformance Test specified in the Yellow book, then a Certification of DLMS/COSEM compliance is issued by the DLMS UA.

The IEC TC13 WG14 groups the DLMS specifications under the common heading: "Electricity metering data exchange - The DLMS/COSEM suite". DLMS/COSEM protocol is not specific to electricity metering, it is also used for gas, water and heat metering.

Other IEC 62056 parts deal with Electricity metering - Data exchange for meter reading, tariff and load control

In DLMS/COSEM, all the data in electronic meters and devices are represented by means of mapping them to appropriate classes and related attribute values. Any real world thing mapped to an appropriate class type can be described by the attributes defined in the standard; and the methods defined therewith allow operations to be performed on the attributes. The attributes and methods constitute an object. Conventionally, the first attribute in any object is the logical_name, also defined as the OBIS code in case of LN referencing. It is one part of the identification of the object. Objects that share common characteristics are generalized as instantiations of an interface class with defined class_id. Instantiations of an interface class are called COSEM objects. IEC 62056-62 defines 19 interface classes for COSEM object model.

IEC 61107 or currently IEC 62056-21, was an international standard for a computer to read utility meters. It is designed to operate over any media, including the Internet. A meter sends ASCII (in modes A..D) or HDLC (mode E) data to a nearby hand-held unit (HHU) using a serial port. The physical media are usually either modulated light, sent with an LED and received with a photodiode, or a pair of wires, usually modulated by a 20mA current loop. The protocol is usually half-duplex.

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