5.8.19.2 ExclusiveLimitStateMachineType

The ExclusiveLimitStateMachineType defines the state machine used by AlarmConditionTypes that handle multiple mutually exclusive limits. It is illustrated in Figure 19.

It is created by extending the FiniteStateMachineType. It is formally defined in Table 93 and the state transitions are described in Table 94.

The component Variables of the ExclusiveLimitStateMachineType have additional Attributes defined in Table 95.

The ExclusiveLimitStateMachineType defines the sub state machine that represents the actual level of a multilevel Alarm when it is in the Active state. The sub state machine defined here includes High, Low, HighHigh and LowLow states. 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 Active state. This Active state could be part of a “level” Alarm or “deviation” Alarm or any other Alarm state machine.

The LowLow, Low, High, HighHigh are 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 AvailableStates and/or AvailableTransitions (see 10000-16).