BACnet.Protocol.EventAlgorithms.UnsignedRange (bacstack v0.0.1)

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Implements the BACnet event algorithm UnsignedRange.

The UnsignedRange event algorithm detects whether the monitored value exceeds a range defined by a high limit and a low limit.

For more specific information about the event algorithm, consult ASHRAE 135 13.3.9.

Summary

Types

t()

Representative type for the event algorithm.

Functions

execute(state)

Calculates the new state for the current state and parameters. Prior to this function invocation, the state should have been updated with update/2, if any of the properties has changed.

new(monitored_value, params)

Creates a new algorithm state.

update(state, params)

Updates the state using the given parameters (monitored_value, parameters, status_flags).

Types

t()

@opaque t()

Representative type for the event algorithm.

Functions

execute(state)

@spec execute(t()) ::
  {:event, new_state :: t(),
   BACnet.Protocol.NotificationParameters.UnsignedRange.t()}
  | {:delayed_event | :no_event, new_state :: t()}

Calculates the new state for the current state and parameters. Prior to this function invocation, the state should have been updated with update/2, if any of the properties has changed.

:delayed_event helps identifying whether the algorithm needs to be called periodically in order to overcome the time_delay and trigger a state change. As soon as :event or :no_event is given as flag, it means the caller can go back to event orientated calling.

The status_flags field of the notifications parameters is updated from the state with the correct in_alarm state, however to ensure the Status Flags have an overall correct status, the user has to make sure all bits are correctly.

ASHRAE 135:

The conditions evaluated by this event algorithm are:

(a) If pCurrentState is NORMAL, and pMonitoredValue is greater than pHighLimit for pTimeDelay, then indicate a transition to the HIGH_LIMIT event state.

(b) If pCurrentState is NORMAL, and pMonitoredValue is less than pLowLimit for pTimeDelay, then indicate a transition to the LOW_LIMIT event state.

(c) Optional: If pCurrentState is HIGH_LIMIT, and pMonitoredValue is less than pLowLimit for pTimeDelay, then indicate a transition to the LOW_LIMIT event state.

(d) If pCurrentState is HIGH_LIMIT, and pMonitoredValue is equal to or less than pHighLimit for pTimeDelayNormal, then indicate a transition to the NORMAL event state. (e) Optional: If pCurrentState is LOW_LIMIT, and pMonitoredValue is greater than pHighLimit for pTimeDelay, then indicate a transition to the HIGH_LIMIT event state.

(f) If pCurrentState is LOW_LIMIT, and pMonitoredValue is equal to or greater than pLowLimit, for pTimeDelayNormal, then indicate a transition to the NORMAL event state.

new(monitored_value, params)

@spec new(non_neg_integer(), BACnet.Protocol.EventParameters.UnsignedRange.t()) :: t()

Creates a new algorithm state.

update(state, params)

@spec update(t(), Keyword.t()) :: t()

Updates the state using the given parameters (monitored_value, parameters, status_flags).