The TransitionVariableType is the base VariableType for Variables that store a Transition that occurred within a StateMachine as a human readable name.

The SourceTimestamp for the value specifies when the Transition occurred. This value may also be exposed with the TransitionTime Property.

The TransitionVariableType is formally defined in Table 3.

Table 3 – TransitionVariableType definition

Attribute

Value

BrowseName

TransitionVariableType

DataType

LocalizedText

ValueRank

−1 (−1 = Scalar)

IsAbstract

False

References

NodeClass

BrowseName

DataType

TypeDefinition

ModellingRule

Subtype of the BaseDataVariableType defined in OPC 10000-5

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

HasSubtype

VariableType

FiniteTransitionVariableType

Defined in 4.4.7

HasProperty

Variable

Id

BaseDataType

PropertyType

Mandatory

HasProperty

Variable

Name

QualifiedName

PropertyType

Optional

HasProperty

Variable

Number

UInt32

PropertyType

Optional

HasProperty

Variable

TransitionTime

UtcTime

PropertyType

Optional

HasProperty

Variable

EffectiveTransitionTime

UtcTime

PropertyType

Optional

Conformance Units

Base Info State Machine Instance

Id is a name which uniquely identifies a Transition within the StateMachineType. A subtype may restrict the DataType.

Name is a QualifiedName which uniquely identifies a transition within the StateMachineType.

Number is an integer which uniquely identifies a transition within the StateMachineType.

TransitionTime specifies when the transition occurred.

EffectiveTransitionTime specifies the time when the current state or one of its substates was entered. If, for example, a StateA is active and – while active – switches several times between its substates SubA and SubB, then the TransitionTime stays at the point in time where StateA became active whereas the EffectiveTransitionTime changes with each change of a substate.