What B-ACC Is
A BACnet device profile is a standardized capability level: a checklist of things a device must be able to do before it can wear the label. B-ACC (BACnet Access Control Controller) is defined in Annex L of ANSI/ASHRAE 135-2024 (clause L.6.2) as the controller that makes access decisions: it evaluates credentials against rights, commands doors, generates access events, and keeps an event history.
The checklist items are BACnet Interoperability Building Blocks (BIBBs). B-ACC is a B-role device. A device documents its claim in its PICS (Protocol Implementation Conformance Statement); to verify a claim, ask for the PICS and check the profile line.
Where It’s Used
B-ACC fits the panel that runs a physical access-control system for a set of doors.
- Access-control panels. A controller that grants or denies entry by matching a credential read at a reader against configured rights, then commands the door.
- Event annunciation. A controller reporting access-granted, access-denied, and door-forced events to the building or security system.
- Integrated security. An access controller surfacing its decisions and history to a BMS or security workstation.
Required Services
The table below is the exhaustive service set required by the B-ACC BIBBs. Initiates means the device sends the request or notification; Executes means the device receives and acts on it (responding, for confirmed services). BIBB codes encode the same split: a -A BIBB is the initiating side, a -B BIBB the executing side. A - means the profile does not require that direction; a device may still support it.
| Capability area | Service | Required by BIBB | Initiates | Executes |
|---|---|---|---|---|
| Data sharing | ReadProperty | DS-RP-B, DS-ACUC-B, DS-ACSC-B | - | Yes |
| Data sharing | ReadPropertyMultiple | DS-RPM-B | - | Yes |
| Data sharing | WriteProperty | DS-WP-B, DS-ACUC-B, DS-ACSC-B | - | Yes |
| Data sharing | WritePropertyMultiple | DS-WPM-B | - | Yes |
| Data sharing | SubscribeCOV | DS-COV-B | - | Yes |
| Data sharing | ConfirmedCOVNotification | DS-COV-B | Yes | - |
| Data sharing | UnconfirmedCOVNotification | DS-COV-B | Yes | - |
| Alarm and event management | ConfirmedEventNotification | AE-AC-B | Yes | - |
| Alarm and event management | UnconfirmedEventNotification | AE-AC-B | Yes | - |
| Alarm and event management | AcknowledgeAlarm | AE-ACK-B | - | Yes |
| Alarm and event management | GetEventInformation | AE-INFO-B | - | Yes |
| Alarm and event management | ReadRange (event log access) | AE-EL-I-B | - | Yes |
| Device and network management | Who-Is | DM-DDB-A, DM-DDB-B | Yes | Yes |
| Device and network management | I-Am | DM-DDB-A, DM-DDB-B | Yes | Yes |
| Device and network management | Who-Has | DM-DOB-B | - | Yes |
| Device and network management | I-Have | DM-DOB-B | Yes | - |
| Device and network management | DeviceCommunicationControl | DM-DCC-B | - | Yes |
| Device and network management | TimeSynchronization ¹ | DM-TS-B | - | Yes |
| Device and network management | UTCTimeSynchronization ¹ | DM-UTC-B | - | Yes |
| Device and network management | ReinitializeDevice | DM-RD-B, DM-BR-B | - | Yes |
| Device and network management | AtomicReadFile (backup) | DM-BR-B | - | Yes |
| Device and network management | AtomicWriteFile (restore) | DM-BR-B | - | Yes |
The access model lives in hosted objects. The DS-ACUC-B and DS-ACSC-B requirements mean the device hosts the access-control object family, Access Point, Access Zone, Access Rights, and Access Credential, read and written with ReadProperty and WriteProperty. AE-EL-I-B means it hosts an Event Log; and SCHED-I-B means it hosts Schedule and Calendar objects, which add no outbound service and so are not rows above.
¹ The profile requires one of the two time-synchronization services, not both. (Protocol_Revision is a readable property of the device’s Device object.)
Related Profiles
| Profile | How it differs from B-ACC |
|---|---|
| B-AACC | Advanced Access Control Controller: adds client-side access services and change-of-value-multiple |
| B-ACDC | Access Control Door Controller: operates door hardware only, without the access decision |
| B-ACCR | Access Control Credential Reader: reads credentials at a door |
What Chipkin Provides
The CAS BACnet Stack implements the access-control object family, the access-event model, and the services the B-ACC profile requires. Talk to us about building or integrating a B-ACC device on the stack.