This VariableTypedefines the general characteristics of a DiscreteItemthat can have two states. The TwoStateDiscreteTypederives from the DiscreteItemType. It is formally defined in Table 4.

Table 4– TwoStateDiscreteType definition

Attribute

Value

BrowseName

TwoStateDiscreteType

IsAbstract

False

ValueRank

−2 (−2 = ‘Any’)

DataType

Boolean

References

NodeClass

BrowseName

DataType

TypeDefinition

ModellingRule

Subtype of the DiscreteItemTypedefined in 5.3.3; i.e the Propertiesof that type are inherited.

HasProperty

Variable

TrueState

LocalizedText

PropertyType

Mandatory

HasProperty

Variable

FalseState

LocalizedText

PropertyType

Mandatory

TrueStatecontains a string to be associated with this DataItemwhen it is TRUE. This is typically used for a contact when it is in the closed (non-zero) state.

for example: "RUN", "CLOSE", "ENABLE", "SAFE“, etc.

FalseStatecontains a string to be associated with this DataItemwhen it is FALSE. This is typically used for a contact when it is in the open (zero) state.

for example: "STOP", "OPEN", "DISABLE", "UNSAFE“, etc.

If the item contains an array, then the Propertieswill apply to all elements in the array.

The StatusCode SemanticsChangedbit shall be set if any of the FalseState or TrueState (changes can cause misinterpretation by users or (scripting) programs) Propertiesare changed (see section 5.2for additional information).