IEC 61850 standard was developed primarily for communication with digital protection relays. Each relay or device internally contains the following structure:

•Logical Devices (LD): These are mapped logical devices that correspond to a real device, such as a Bay, mapped inside a relay. A Logical Device is always mapped to a single IED (Intelligent Electronic Device), because Logical Devices are not distributed

•Logical Nodes (LN): These are functions from a real device mapped to a Logical Device. For example, a virtual representation of a switch (Circuit Breaker) in a Bay is a Logical Node, which contains a standard class name defined as XCBR. Usually a Logical Device is formed by several Logical Nodes

•Data Objects (DO) and Data Attributes (DA): Information inside a Logical Node is organized in sets of specific data (Data Objects) and the properties inside each set are Data Attributes. The set of all Data Attributes from a Data Object is called CDC (Common Data Class)

•Functional Constraint (FC): These are specific services that can be used in each Data Attribute. FCs may also be part of a variable's path, depending on the configuration of a device

The format used by this Driver for all Tags representing Data Objects or Data Attributes is the following:

•Device: Server:LD, such as "ArevaP139:UPC12AL1Control"

•Item: LN$FC$Data$DataAttribute, such as "XCBR1$ST$Mod$stVal"