When communicating with the DLMS/COSEM protocol, it is necessary to configure the relational-level protocols separately. (The IEC62056-21 protocol integrates both the relational and application levels at the same time.) Depending on the type of meter and the type of physical connection, we choose between these protocols.

• HDLC (IEC 62056-46) – Used usually on the serial line and for EMH and Landis+Gyr electricity meters also with TCP/IP. Communication parameters include:
  • physical device address,
  • logical device address,
  • ID of the connecting client (defines the role of the client)
• COSEM transport for IPv4 (IEC 62056-47) - also referred to as DLMS/COSEM Wrapper (Wrapper for short). Communication parameters include:
  • logical device address
  • address of the connecting client (defines the role of the client)
• IEC 62056-21 - also referred to as IEC21 for short. It is also an application layer protocol. The communication parameter is the serial number of the meter, which is optional if the communication takes place via TCP/IP or an optical head.