The OPC UA LogObject model defines two well-known instances; ServerLog and Logs (see Table 20 and Table 21 and Figure 7). LogObjects may also exist in other locations in the AddressSpace. The ServerLog is a well-known instance that, if implemented, provides all LogRecords for the Server. The Logs object provides a central folder from which all LogObject instances can be found.

Figure 7 – ServerLog & Logs illustration

The following instance can exist in Servers if they support LogObjects. It is formally defined in Table 20.

Table 20 – ServerLog definition

Attribute	Value
BrowseName	ServerLog
References	NodeClass	BrowseName	DataType	TypeDefinition
Organized by the Server Object defined in OPC 10000-5
HasTypeDefinition	ObjectType	0:LogObjectType
ConformanceUnits
LogObject ServerLog

The ServerLog is a LogObject that collects diagnostic information for a Server if it is provided. The ServerLog exposes all LogRecords available in the Server (this shall include all LogRecords in all other LogObjects in the Server).

This Object provides a folder that when Organize references are followed, will resolve to all LogObjects defined in the Server (I.e. they are either directly or indirectly referenced from this folder as part of the tree). This folder shall only contain reference to instances of LogObjectType (or subtype of LogObjectType) and references to instance of FolderType(or Sub types of FolderType).

The Logs Object is the target of an Organizes reference from the Resources Object defined in OPC 10000-22.

Its representation in the AddressSpace is formally defined in Table 21.

Table 21 – Logs Object Definition

Attribute	Value
BrowseName	Logs
References	NodeClass	BrowseName	DataType	TypeDefinition
Organized by the Resources Object defined in OPC 10000-22
HasTypeDefinition	ObjectType	0:FolderType
ConformanceUnits
LogObject Logs

– LogObject Server Examples (Informative)