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BACnet Object type lookup

BACnet ANSI/ASHRAE 135-2020 defines 60+ Object types grouped by category: Analog, Binary, Multistate, Device, Time, Data, Security, Misc. Each has a different Present_Value type (REAL, BINARY, UNSIGNED, STRUCTURE…) and a set of supported BACnet services. Filter by category or search by name/abbreviation for the right reference.

Free · no sign-upLast updated: 2026-05-20
20 result(s)
  • #0Analog InputAI
    Analog
    Present_Value
    REAL
    Main services
    ReadProperty, WriteProperty (limited), SubscribeCOV

    READ ONLY sensor (measured T°, pressure). Not writable from the supervisor.

  • #1Analog OutputAO
    Analog
    Present_Value
    REAL
    Main services
    ReadProperty, WriteProperty, SubscribeCOV

    Physical analogue command (0-10 V signal to a valve, drive). Writable.

  • #2Analog ValueAV
    Analog
    Present_Value
    REAL
    Main services
    ReadProperty, WriteProperty, SubscribeCOV

    Virtual variable (setpoint, offset). Writable. Not wired to a physical signal.

  • #3Binary InputBI
    Binary
    Present_Value
    BINARY (0/1)
    Main services
    ReadProperty, SubscribeCOV

    Dry contact input (alarm state, switch). READ ONLY.

  • #4Binary OutputBO
    Binary
    Present_Value
    BINARY (0/1)
    Main services
    ReadProperty, WriteProperty, SubscribeCOV

    Binary output relay (boiler, pump command). Writable.

  • #5Binary ValueBV
    Binary
    Present_Value
    BINARY (0/1)
    Main services
    ReadProperty, WriteProperty, SubscribeCOV

    Virtual binary variable (auto/manual mode). Writable.

  • #13Multi-state InputMSI
    Multi-state
    Present_Value
    UNSIGNED
    Main services
    ReadProperty, SubscribeCOV

    Multi-state READ ONLY (HVAC mode, valve position). UNSIGNED enumeration.

  • #14Multi-state OutputMSO
    Multi-state
    Present_Value
    UNSIGNED
    Main services
    ReadProperty, WriteProperty, SubscribeCOV

    Multi-state command (HVAC mode from supervisor). Writable.

  • #19Multi-state ValueMSV
    Multi-state
    Present_Value
    UNSIGNED
    Main services
    ReadProperty, WriteProperty, SubscribeCOV

    Virtual multi-state variable. Writable.

  • #8DeviceDEV
    Device
    Present_Value
    — (no PV)
    Main services
    ReadProperty, Who-Is / I-Am, AtomicReadFile (config)

    BACnet device identity. Object_Identifier (Device, instance) unique inter-network.

  • #17ScheduleSCH
    Time
    Present_Value
    ANY
    Main services
    ReadProperty, WriteProperty

    Time programming (setpoints by day/week). Writable.

  • #6CalendarCAL
    Time
    Present_Value
    BOOLEAN (active dates)
    Main services
    ReadProperty, WriteProperty

    Exception calendar (holidays, special periods). Referenced by Schedule.

  • #20Trend LogTL
    Data
    Present_Value
    STRUCTURE
    Main services
    ReadProperty, ReadRange

    Historical log of an Object's property (T° every 5 min over 30 days).

  • #27Trend Log MultipleTLM
    Data
    Present_Value
    STRUCTURE
    Main services
    ReadProperty, ReadRange

    Historical log of multiple Objects in parallel (T°/flow correlations).

  • #15Notification ClassNC
    Security
    Present_Value
    STRUCTURE
    Main services
    ReadProperty, WriteProperty, ConfirmedEventNotification

    Alarm recipient config (supervisors receiving ConfirmedEventNotification).

  • #12Loop (PID)LOOP
    Analog
    Present_Value
    REAL
    Main services
    ReadProperty, WriteProperty

    Dedicated PID loop (setpoint, measure, output, gains). Embedded controller.

  • #23AccumulatorACC
    Data
    Present_Value
    UNSIGNED
    Main services
    ReadProperty, SubscribeCOV

    Incremental counter (energy, water, gas). Used for sub-metering in regulated buildings.

  • #39Bitstring ValueBSV
    Misc
    Present_Value
    BITSTRING
    Main services
    ReadProperty, WriteProperty

    Configurable bit field (vendor-specific status flags).

  • #40CharacterString ValueCSV
    Misc
    Present_Value
    CHARACTER_STRING
    Main services
    ReadProperty, WriteProperty

    Text variable (zone name, error message).

  • #54Lighting OutputLO
    Misc
    Present_Value
    REAL
    Main services
    ReadProperty, WriteProperty, SubscribeCOV

    Lighting control Object (intensity, ramping). BACnet 135.1-2021.

How to use

1. Type a name ("Analog Input"), abbreviation ("AI") or type ID (0). 2. Or filter by category (Analog, Binary, Multistate…). 3. The card gives you Present_Value, mandatory services, and a BMS-context note. 4. For the full list of 60+ types, see ANSI/ASHRAE 135 Clause 12.

Go deeper

Subset extracted from ANSI/ASHRAE 135-2020 Clause 12. For the exhaustive list and BACnet/SC protocols, see the official specification. Independent CertifBus tool.

Last updated: 2026-05-20

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