What B-SS 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-SS (BACnet Smart Sensor) is defined in Annex L of ANSI/ASHRAE 135-2024 (clause L.4.5) as a simple sensing device with very limited resources. It is the smallest standardized profile.
The checklist items are BACnet Interoperability Building Blocks (BIBBs), each a named unit of capability. B-SS requires exactly one: the ability to provide the value of any of its objects on request. It has no write, alarming, scheduling, trending, or device-management 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-SS fits a networked sensor that only needs to report a reading.
- Networked sensors. A temperature, humidity, or CO2 sensor that exposes its value as an Analog Input and does nothing else over BACnet.
- Meter interfaces. A simple device reporting a metered value for a supervisory controller to read.
- Read-only points on a field bus. A device on an MS/TP trunk whose entire job is to answer reads.
Required Services
The table below is the exhaustive service set required by the B-SS BIBBs. Executes means the device receives and acts on it (responding, for confirmed services). BIBB codes encode the direction: a -B BIBB is the executing side.
| Capability area | Service | Required by BIBB | Initiates | Executes |
|---|---|---|---|---|
| Data sharing | ReadProperty | DS-RP-B | - | Yes |
That single row is the whole profile. A real B-SS device usually also answers Who-Is so it can be discovered, but the profile does not require it: on an MS/TP subordinate segment the master polls the sensor directly, so even discovery can be omitted.
Related Profiles
| Profile | How it differs from B-SS |
|---|---|
| B-SA | Smart Actuator: adds the ability to accept writes and drive an output |
| B-ASC | Application Specific Controller: adds writes, discovery, and communication control |
| B-AAC | Advanced Application Controller: adds alarming and local scheduling |
What Chipkin Provides
The CAS BACnet Stack implements the ReadProperty capability the B-SS profile requires, and far more; a smart sensor is the simplest thing the stack can build. Talk to us about building or integrating a B-SS device on the stack.