The LogObjectType is formally defined in Table 1. The LogRecord structure that is returned by the GetRecords Method is described in 5.4.

Table 1 – LogObjectType definition

Attribute	Value
BrowseName	0:LogObjectType
IsAbstract	False
References	NodeClass	BrowseName	DataType	TypeDefinition	Other
Subtype of the 0:BaseObjectType defined in OPC 10000-5
0:HasComponent	Method	0:GetRecords	Defined in 5.3		M
0:HasProperty	Variable	0:MaxRecords	0:UInt32	0:PropertyType	O
0:HasProperty	Variable	0:MaxStorageDuration	0:Duration	0:PropertyType	O
0:HasProperty	Variable	0:MinimumSeverity	0:UInt16	0:PropertyType	O
ConformanceUnits
LogObject Base

Optional MaxRecords defines the maximum number of records in a buffer associated with this LogObject. When this maximum is reached, a new log record will trigger the deletion of the oldest record. If this Variable is not provided, then there is no Server published limit on the log buffer. Zero is an invalid value for MaxRecords. The LogRecord Structure is defined in 5.4.

Optional MaxStorageDuration defines the maximum time period that the LogObject will buffer log entries in the LogObject. Records that are older than the maximum duration may be deleted. If this Variable is not provided than no maximum duration is configured. Zero is an invalid duration. In the case of persistent storage, on startup a number of records may be deleted, depending on the duration of the downtime for the application.

The two maximum settings are used to limit the storage requirements for a Server. MaxRecords is typically a hard limit while MaxStorageDuration is more a soft limit in that LogRecords may be retained past the MaxStorageDuration if space allows. If MaxRecords is exceeded before MaxStorageDuration, the system should generate a LogOverflowEventType warning Event indicating an overflow of LogRecords (see 6.4).

The MinimumSeverity describes the minimum Severity associated with a LogRecord that is stored. LogRecords with a Severity that is less then this number will not be stored in this LogObject. If omitted, there is no restriction on the Severity associated with LogRecords that are stored. This number shall be between 0 and 1000, any other number is illegal. Servers can allow this value to be written. The Severity is only checked when a LogRecord is being generated, a change to the value does not affect the records that are already stored.