What B-LS 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-LS (BACnet Lighting Supervisor) is defined in Annex L of ANSI/ASHRAE 135-2024 (clause L.11.1) as a device that implements Channel objects, optionally drives its own lighting outputs, and forwards channel writes to other BACnet devices.
The checklist items are BACnet Interoperability Building Blocks (BIBBs). B-LS is the coordinating tier of lighting control: it takes a group command and propagates it across many lighting devices. 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-LS fits the controller that turns a single lighting scene or group command into writes across many fixtures.
- Scene and group control. A supervisor that applies a scene by writing a Channel object, which fans the value out to member lighting objects.
- Cross-device lighting. A device propagating channel values to Lighting Output objects in other devices.
- Scheduled lighting. A supervisor running time-of-day lighting schedules in itself and in downstream devices.
Required Services
The table below is the exhaustive service set required by the B-LS 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 | - | Yes |
| Data sharing | WriteProperty | DS-WP-A, DS-WP-B, DS-ALO-A | Yes | Yes |
| Data sharing | WriteGroup | DS-WG-E-B | - | Yes |
| Scheduling | WriteProperty (schedule write-out to other devices) | SCHED-E-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 |
The group behavior lives in hosted objects. A B-LS device hosts Channel objects that receive WriteGroup commands and propagate the value to their member references, and Schedule and Calendar objects for scheduled lighting. The DS-ALO-A requirement is what lets the supervisor initiate WriteProperty to lighting objects in other devices.
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-LS |
|---|---|
| B-LD | Lighting Device: the endpoint that drives a light, without the Channel and forwarding capability |
| B-ALCS | Advanced Lighting Control Station: an operator-side station that commands lighting |
| B-BC | Building Controller: the general controller, without the lighting Channel and WriteGroup model |
What Chipkin Provides
The CAS BACnet Stack implements the Channel object, WriteGroup handling, external write-out, and the services the B-LS profile requires. Talk to us about building or integrating a B-LS device on the stack.