4.6.4 GuardVariableType
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 22.
| Attribute | Value | ||||
| BrowseName | GuardVariableType | ||||
| DataType | LocalizedText | ||||
| ValueRank | −1 (−1 = Scalar) | ||||
| IsAbstract | False | ||||
| References | NodeClass | BrowseName | DataType | TypeDefinition | ModellingRule |
|---|---|---|---|---|---|
| Subtype of the BaseDataVariableType defined in OPC 10000-5 | |||||
| HasSubtype | VariableType | ElseGuardVariableType | Defined in 4.6.6 | ||
| HasSubtype | VariableType | ExpressionGuardVariableType | Defined in 4.6.5 | ||
| Conformance Units | |||||
|---|---|---|---|---|---|
| Base Info Choice States |