IEC 61850 Domain Knowledge

Product Model (IED hierarchy)

IED → Server → LDevice → LNode (LN) → DataObject (DO) → DataAttribute (DA)

IED: physical device (relay, controller)
Server: communication entity exposing data via MMS
LDevice: logical grouping within a server; must contain LN0
LNode: fundamental function unit (e.g. PTOC=overcurrent, MMXU=measurement)
DataObject (DO): specific information within LN; may contain sub-dataobjects (SDOs)
DataAttribute (DA): leaf level — holds value, quality, timestamp; may be basic (BDA) or structured

Substation → VoltageLevel → Bay → Equipment/Function → SubEquipment/SubFunction

Describes electrical topology independently of which IED hosts the data.

IED → Server → LDevice → LNode (LN) → DataObject (DO) → DataAttribute (DA)

IED: physical device (relay, controller)
Server: communication entity exposing data via MMS
LDevice: logical grouping within a server; must contain LN0
LNode: fundamental function unit (e.g. PTOC=overcurrent, MMXU=measurement)
DataObject (DO): specific information within LN; may contain sub-dataobjects (SDOs)
DataAttribute (DA): leaf level — holds value, quality, timestamp; may be basic (BDA) or structured

Substation → VoltageLevel → Bay → Equipment/Function → SubEquipment/SubFunction

Describes electrical topology independently of which IED hosts the data.