BACnet.Protocol.EventTransitionBits (bacstack v0.1.0-dev.1)

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Event Transition Bits is a three-bit bit string used throughout the BACnet event and alarm model. Each bit corresponds to one of the three possible state transitions an object can make:

BitTransitionMeaning (when TRUE)
0TO_OFFNORMALTransition into an off-normal event state
1TO_FAULTTransition into a fault event state
2TO_NORMALTransition back to the normal state

Primary uses:

  • Event_Enable property - which transitions should generate notifications
  • Acked_Transitions - which transitions still require operator acknowledgment
  • Various alarm/event summary services and notification parameters

The bit positions and semantics are identical for intrinsic reporting, algorithmic reporting, and all the summary/notification services.

BACnet Specification References

  • ASN.1 (Clause 21): BACnetEventTransitionBits ::= BIT STRING { to-offnormal (0), to-fault (1), to-normal (2) }
  • Object properties (Clause 12): event_enable, acked_transitions, event_time_stamps, etc.
  • Services: GetAlarmSummary, GetEventInformation, Confirmed/UnconfirmedEventNotification.

Examples (Doc Test)

iex> bits = %EventTransitionBits{to_offnormal: true, to_fault: true, to_normal: false}
iex> bits.to_offnormal
true

See Also

Summary

Types

t()

Represents a bit string indicating which event state transitions are of interest (to-offnormal, to-fault, to-normal).

Functions

encode(flags, opts \\ [])

Encodes a BACnet event transition bits into application tags encoding.

from_bitstring(bitstring)

Creates from an application tag bitstring an event transition bits.

parse(tags)

Parses a BACnet event transition bits from application tags encoding.

to_bitstring(t)

Creates an application tag bitstring from an event transition bits.

valid?(t)

Validates whether the given event transition bits is in form valid.

Types

t()

@type t() :: %BACnet.Protocol.EventTransitionBits{
  to_fault: boolean(),
  to_normal: boolean(),
  to_offnormal: boolean()
}

Represents a bit string indicating which event state transitions are of interest (to-offnormal, to-fault, to-normal).

Functions

encode(flags, opts \\ [])

@spec encode(t(), Keyword.t()) ::
  {:ok, BACnet.Protocol.ApplicationTags.encoding_list()} | {:error, term()}

Encodes a BACnet event transition bits into application tags encoding.

from_bitstring(bitstring)

@spec from_bitstring(tuple()) :: t()

Creates from an application tag bitstring an event transition bits.

parse(tags)

@spec parse(BACnet.Protocol.ApplicationTags.encoding_list()) ::
  {:ok, {t(), rest :: BACnet.Protocol.ApplicationTags.encoding_list()}}
  | {:error, term()}

Parses a BACnet event transition bits from application tags encoding.

to_bitstring(t)

@spec to_bitstring(t()) :: BACnet.Protocol.ApplicationTags.primitive_encoding()

Creates an application tag bitstring from an event transition bits.

valid?(t)

@spec valid?(t()) :: boolean()

Validates whether the given event transition bits is in form valid.

It only validates the struct is valid as per type specification.