Terminology1.8.DescriptionTermAn abnormal state of a condition.AlarmAn OPC service for providing information about alarms andevents to OPC clients.Alarms and Events; AEAn OPC service for providing information about process data toOPC clients.Data Access; DAPart of a logical node object representing specific information,for example, status, or measurement. From an object-orientedpoint of view, a data object is an instance of a class data object.DOs are normally used as transaction objects; that is, they aredata structures.Data Object; DOThe data set is the content basis for reporting and logging. Thedata set contains references to the data and data attribute val-ues.Data SetA physical device that behaves as its own communication nodein the network, for example, protection relay.DeviceChange of process data or an OPC internal value. Normally, anevent consists of value, quality, and timestamp.EventA physical IEC 61850 device that behaves as its own commu-nication node in the IEC 61850 protocol.Intelligent Electronic DeviceRepresentation of a group of functions. Each function is definedas a logical node. A physical device consists of one or severalLDs.Logical Device; LDThe smallest part of a function that exchanges data. An LN isan object defined by its data and methods.Logical Node; LNA communication protocol developed by Echelon.LONA proprietary method of ABB on top of the standard LON pro-tocol.LON Application Guideline forsubstation automation; LAGSeries of standards specifications aiming at open connectivityin industrial automation and the enterprise systems that supportindustry.OPCRepresentation of a connection to the data source within theOPC server. An OPC item is identified by a string