This clause describes the state machine and the base AlarmType behaviour for AlarmConditionTypeswith multiple mutually exclusive limits.

The ExclusiveLimitStateMachineTypedefines the state machine used by AlarmConditionTypesthat handle multiple mutually exclusive limits. It is illustrated in Figure 17.

image020.png

Figure 17– ExclusiveLimitStateMachineType

It is created by extending the FiniteStateMachineType. It is formally defined in Table 61and the state transitions are described in Table 62.

Table 61– ExclusiveLimitStateMachineType definition

Attribute

Value

BrowseName

ExclusiveLimitStateMachineType

IsAbstract

False

References

NodeClass

BrowseName

DataType

TypeDefinition

ModellingRule

Subtype of the FiniteStateMachineType

HasComponent

Object

HighHigh

StateType

HasComponent

Object

High

StateType

HasComponent

Object

Low

StateType

HasComponent

Object

LowLow

StateType

HasComponent

Object

LowToLowLow

TransitionType

HasComponent

Object

LowLowToLow

TransitionType

HasComponent

Object

HighToHighHigh

TransitionType

HasComponent

Object

HighHighToHigh

TransitionType

Table 62– ExclusiveLimitStateMachineType transitions

BrowseName

References

BrowseName

TypeDefinition

Transitions

HighHighToHigh

FromState

HighHigh

StateType

ToState

High

StateType

HasEffect

AlarmConditionType

HighToHighHigh

FromState

High

StateType

ToState

HighHigh

StateType

HasEffect

AlarmConditionType

LowLowToLow

FromState

LowLow

StateType

ToState

Low

StateType

HasEffect

AlarmConditionType

LowToLowLow

FromState

Low

StateType

ToState

LowLow

StateType

HasEffect

AlarmConditionType

The ExclusiveLimitStateMachineTypedefines the sub state machine that represents the actual level of a multilevel Alarm when it is in the Activestate. The sub state machine defined here includes High, Low, HighHighand LowLowstates. This model also includes in its transition state a series of transition to and from a parent state, the inactive state. This state machine as it is defined shall be used as a sub state machine for a state machine which has an Activestate. This Activestate could be part of a “level” Alarmor “deviation” Alarmor any other Alarmstate machine.

The LowLow, Low, High, HighHighare typical for many industries. Vendors can introduce sub-state models that include additional limits; they may also omit limits in an instance. If a model omits states or transitions in the StateMachine, it is recommended that they provide the optional Property AvailableStatesand/or AvailableTransitions(see OPC 10000-5).

The ExclusiveLimitAlarmTypeis used to specify the common behaviour for Alarm Typeswith multiple mutually exclusive limits. The ExclusiveLimitAlarmTypeis illustrated in Figure 18.

image021.png

Figure 18– ExclusiveLimitAlarmType

The ExclusiveLimitAlarmTypeis formally defined in Table 63.

Table 63– ExclusiveLimitAlarmType definition

Attribute

Value

BrowseName

ExclusiveLimitAlarmType

IsAbstract

False

References

NodeClass

BrowseName

DataType

TypeDefinition

ModellingRule

Subtype of the LimitAlarmType defined in clause 5.8.11.

HasSubtype

ObjectType

ExclusiveLevelAlarmType

Defined in Clause 5.8.14.3

HasSubtype

ObjectType

ExclusiveDeviationAlarmType

Defined in Clause 5.8.15.3

HasSubtype

ObjectType

ExclusiveRateOfChangeAlarmType

Defined in Clause 5.8.16.3

HasComponent

Object

LimitState

ExclusiveLimitStateMachineType

Mandatory

The LimitStateis a sub state of the ActiveState and has an IsTrueSubStateOfreference to the ActiveState. The LimitStaterepresents the actual limit that is violated in an instance of ExclusiveLimitAlarmType. When the ActiveStateof the AlarmConditionTypeis inactive the LimitStateshall not be available and shall return NULL on read. Any Eventsthat subscribe for fields from the LimitStatewhen the ActiveStateis inactive shall return a NULL for these unavailable fields.