IEC60870533
IEC 60870-5-33 is a part of the IEC 60870 series of standards that defines the application layer for telecontrol, teleprotection, and associated telecommunications for electrical power systems. Specifically, IEC 60870-5-33 deals with the definition of the application service data units (ASDU) used in the IEC 60870-5 protocol. The ASDU is the fundamental structure for exchanging information between a master station and a remote slave station in a telecontrol system.
This standard specifies the format and content of ASDUs, including information objects and their associated type