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4.6 StateMachine Extensions for ChoiceStates and Guards ToC Previous Next

4.6.4 GuardVariableType ToC Previous Next index

The GuardVariableType provides the information of a Guard of a Transition in a StateMachine. A Guard indicates, if the Transition can be used or not. The Guard defines a semantic that can be evaluated to “True” or “False”. Only if the semantic is “True”, the Transition connected via a HasGuard Reference can be used. The value of the GuardVariableType provides the semantic of the Guard in a human-readable way, that can be used to display the StateMachine.

This base GuardVariableType does not define a machine-readable semantic of the Guard. The calculation, if the Guard is “True” or “False” is server-specific. Subtypes of this VariableType do define concrete machine-readable semantics.

The GuardVariableType is formally defined in Table 20.

Table 20 – GuardVariableType definition

Attribute Value
BrowseName GuardVariableType
DataType LocalizedText
ValueRank −1 (−1 = Scalar)
IsAbstract False

Subtype of the BaseDataVariableType defined in Clause OPC 10000-5.

Note that a Reference to this subtype is not shown in the definition of the BaseDataVariableType.

References NodeClass BrowseName DataType TypeDefinition ModellingRule
HasSubtype VariableType ElseGuardVariableType Defined in Clause 4.6.6    
HasSubtype VariableType ExpressionGuardVariableType Defined in Clause 4.6.5    
Conformance Units          
Base Info Choice States          

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