The GuardVariableTypeprovides the information of a Guardof a Transitionin a StateMachine. A Guardindicates, if the Transitioncan be used or not. The Guarddefines a semantic that can be evaluated to "True" or "False". Only if the semantic is "True", the Transitionconnected via a HasGuard Referencecan be used. The value of the GuardVariableTypeprovides the semantic of the Guardin a human-readable way, that can be used to display the StateMachine.
This base GuardVariableTypedoes not define a machine-readable semantic of the Guard. The calculation, if the Guardis "True" or "False" is server-specific. Subtypes of this VariableTypedo define concrete machine-readable semantics.
The GuardVariableTypeis formally defined in Table 20.
Table 20– GuardVariableType definition
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Attribute |
Value |
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BrowseName |
GuardVariableType |
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DataType |
LocalizedText |
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ValueRank |
−1 (−1 = Scalar) |
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IsAbstract |
False |
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References |
NodeClass |
BrowseName |
DataType |
TypeDefinition |
ModellingRule |
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Subtype of the BaseDataVariableType defined in Clause OPC 10000-5. Note that a Referenceto this subtype is not shown in the definition of the BaseDataVariableType. |
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HasSubtype |
VariableType |
ElseGuardVariableType |
Defined in Clause 4.6.6 |
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HasSubtype |
VariableType |
ExpressionGuardVariableType |
Defined in Clause 4.6.5 |
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Conformance Units |
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Base Info Choice States |
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