What B-SA 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-SA (BACnet Smart Actuator) is defined in Annex L of ANSI/ASHRAE 135-2024 (clause L.4.4) as a simple control device with limited resources, intended for a specific application.
The checklist items are BACnet Interoperability Building Blocks (BIBBs), each a named unit of capability such as “can accept a write” (DS-WP-B). B-SA is nearly minimal: it serves its values, accepts writes to drive its output, and answers discovery. It has no alarming, scheduling, trending, or communication-control requirement. 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-SA fits a networked actuator that takes a command and moves, with just enough BACnet to be discovered and written.
- Networked valve and damper actuators. A device that exposes a commandable Analog Output and drives to whatever the supervisory controller writes.
- Simple relay and output modules. A packaged output device controlled over BACnet with no local logic.
- Actuators on a field bus. A device on an MS/TP trunk that only needs to be read and commanded.
Required Services
The table below is the exhaustive service set required by the B-SA 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 | - | 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 | - |
A device on an MS/TP segment configured as a subordinate may be exempt from the dynamic-binding rows (DM-DDB-B, DM-DOB-B).
Related Profiles
| Profile | How it differs from B-SA |
|---|---|
| B-SS | Smart Sensor: read-only. Serves values but has no write requirement |
| B-ASC | Application Specific Controller: adds the communication-control requirement |
| B-AAC | Advanced Application Controller: adds alarming and local scheduling |
What Chipkin Provides
The CAS BACnet Stack implements the full BIBB set the B-SA profile requires, including priority-array handling for the actuator’s commandable output. Talk to us about building or integrating a B-SA device on the stack.