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COSEM object definitions

Interface classes - OBIS codes -Data types

COSEM object definitions specify valid combinations of interface classes, OBIS codes and data types allowed. They are used by the DLMS UA Conformance Test Tool during testing the COSEM objects.

The DLMS UA Blue Book models metering functions using the COSEM object model that comprises the COSEM interface class (IC) specifications and the OBIS Object Identification System.

The OBIS codes are the Logical Names of the COSEM objects, i.e. the instances of COSEM interface classes.

The combination of the interface class_id and the OBIS code always uniquely identifies each and every object within the server.

The COSEM object definitions file specifies the standard combinations of COSEM interface classes and OBIS codes. It also specifies the data types allowed in those cases where the Blue Book allows a CHOICE.

A new version is generated when:

  • new COSEM interface classes are specified;
  • new OBIS codes are allocated; or 
  • new data types are allocated.


Currently, the following media are supported:

  • Abstract;
  • Electricity;
  • Gas.


The CTT uses .dat files generated from the COSEM object definition spreadsheet files. They can be downloaded from the Euro DCS DLMS-CTT site, using the CTT credentials.

The appropriate .dat files have to be saved in the directory where the CTT is installed.