What B-LD 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-LD (BACnet Lighting Device) is defined in Annex L of ANSI/ASHRAE 135-2024 (clause L.11.2) as a device that implements Lighting Output and/or Binary Lighting Output objects: the endpoint that actually drives a light.
The checklist items are BACnet Interoperability Building Blocks (BIBBs). B-LD is a B-role device that serves and accepts writes to its lighting outputs. 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-LD fits a networked lighting endpoint driven by a lighting control system.
- Dimmable fixtures and drivers. A device exposing a Lighting Output that ramps and fades a dimmable load.
- Relay lighting. A switched-load device exposing a Binary Lighting Output.
- Zone lighting controllers. A device driving one or more lighting channels that a supervisor commands.
Required Services
The table below is the exhaustive service set required by the B-LD 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-B, DS-LO-B, DS-BLO-B | - | Yes |
| Device and network management | Who-Is | DM-DDB-B | - | Yes |
| Device and network management | I-Am | DM-DDB-B | 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 lighting endpoint is modeled as hosted objects. A B-LD device implements at least one Lighting Output (DS-LO-B) or Binary Lighting Output (DS-BLO-B) object, which carry the fade, ramp, and blink behavior a lighting command drives. Reading and writing those objects is the ReadProperty and WriteProperty surface 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-LD |
|---|---|
| B-LS | Lighting Supervisor: adds Channel objects, WriteGroup, and the ability to forward channel writes to other devices |
| B-LCS | Lighting Control Station: the switch or keypad that commands lighting rather than driving it |
| B-SA | Smart Actuator: a general commandable output, without the lighting-specific object model |
What Chipkin Provides
The CAS BACnet Stack implements the Lighting Output and Binary Lighting Output objects and the services the B-LD profile requires. Talk to us about building or integrating a B-LD device on the stack.