Various information elements of a Conditionare not considered to be states. However, a change in their value is considered important and supposed to trigger an Event Notification. These information elements are called ConditionVariable.
ConditionVariablesare represented by a ConditionVariableType,formally defined in Table 4.
Table 4– ConditionVariableType definition
|
Attribute |
Value |
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|
BrowseName |
ConditionVariableType |
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|
DataType |
BaseDataType |
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|
ValueRank |
-2 (-2 = Any) |
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|
IsAbstract |
False |
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|
References |
NodeClass |
BrowseName |
DataType |
TypeDefinition |
ModellingRule |
|
|
Subtype of the BaseDataVariableTypedefined in 10000-5. |
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|
HasProperty |
Variable |
SourceTimestamp |
UtcTime |
PropertyType |
Mandatory |
|
|
ConformanceUnits |
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|
A & C Basic |
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SourceTimestampindicates the time of the last change of the Valueof this ConditionVariable. It shall be the same time that would be returned from the Read Serviceinside the DataValuestructure for the ConditionVariable Value Attribute.