BACnet B-BC (Building Controller) - C++ example

A tutorial example showing how to implement as much of the BACnet B-BC (Building Controller) device profile as the CAS BACnet Stack supports today, in C++. This is the largest single profile in the CAS BACnet Stack example set: commandable outputs, DeviceCommunicationControl, intrinsic alarming with a writable event-recipient list, time synchronisation, ReinitializeDevice, Backup and Restore, a Schedule that writes a remote device's object (SCHED-E-B), and trending (Trend Log, Trend Log Multiple, and ReadRange). It listens on BACnet/IP (UDP 47808) and claims only B-BC.

Download a prebuilt binary (Windows and Linux x64) - or build it yourself, see Build below.

TUTORIAL.md - how to extend this example and how to review it for conformance. Read it when you start turning this into your own device.
docs/PICS.md - the Protocol Implementation Conformance Statement: every object, every property, and who answers it.

Versions: this document describes example v1.0.2, built and verified against CAS BACnet Stack 6.0.21 (issues/runbook @ a8d3b6bf, ahead of 6.x - see TODO.md for why), at Protocol_Revision 26, with the vendored common/ helper at v2.8.0. Running the example prints all three - if what it prints disagrees with this line, trust the program and check CHANGELOG.md.

B-BC is not fully claimable with the standard stack yet. This example implements every B-BC capability the standard CAS BACnet Stack exposes, and clearly marks what it cannot do - see TUTORIAL.md and TODO.md. In summary: Trend Log 1 ("Lilac") demonstrates SetTrendLogStartStopTime's correct usage but a confirmed stack defect (#2051) leaves its Record_Count at 0 - Trend Log Multiple 1 ("Magenta") is the live-verified, working polled-logging + ReadRange demonstration instead; AddTrendLogObject also causes a non-fatal internal log flood (#2050); Calendar 1 ("Cream")'s Date_List cannot be populated (issue #963); and Schedule 1's SCHED-E-B remote write is correctly wired but was not wire-verified cross-instance in a single-host test topology.

What is a B-BC (Building Controller) profile?

A B-BC is the flagship BACnet controller: it serves and commands data, generates and acknowledges alarms, runs a Schedule that can write a remote device's object, trends values over time, synchronises time, accepts DeviceCommunicationControl and ReinitializeDevice, and supports Backup and Restore. Required BIBBs at Protocol_Revision 24: DS-RP-A,B, DS-RPM-A,B, DS-WP-A,B, DS-WPM-B; AE-N-I-B, AE-ACK-B, AE-INFO-B, AE-CRL-B; SCHED-E-B; T-VMT-I-B, T-ATR-B; DM-DDB-A,B, DM-DOB-B, DM-DCC-B, DM-TS-B (or DM-UTC-B), DM-RD-B, DM-BR-B. AE-ESUM-B (GetAlarmSummary) is deliberately omitted - it is not required at or above Protocol_Revision 13.

The device this example creates

Device 389005            "Rainbow"     (instance configurable with --deviceID)
Analog Input  1          "Bronze"      (REAL, degrees Celsius; read-only)
Binary Input  1          "Emerald"     (active / inactive; read-only)
Multi-state Input 1      "Hot Pink"    (state 1..3; read-only)
Analog Output 1          "Chartreuse"  (REAL setpoint; WRITABLE, commandable)
Binary Output 1          "Fuchsia"     (active / inactive; WRITABLE, commandable)
Multi-state Output 1     "Indigo"      (state 1..3; WRITABLE, commandable)
Analog Value 1           "Diamond"     (REAL, WRITABLE; intrinsic OutOfRange alarm)
Notification Class 1     "Crimson"     (routes Diamond's alarms; Recipient_List WRITABLE)
Network Port 1           "Vermilion"   (BACnet/IP - required)
Schedule 1               "Saffron"     (drives Chartreuse locally AND a remote peer - SCHED-E-B)
Calendar 1               "Cream"       (see TUTORIAL.md - Date_List not evaluated)
File 1                   "Ivory"       (backup/restore payload - DM-BR-B)
Trend Log 1              "Lilac"       (polls Bronze; see TUTORIAL.md for a known gap)
Trend Log Multiple 1     "Magenta"     (polls Bronze/Diamond/Chartreuse - the working demo)

What this example supports

BIBBs (BACnet Interoperability Building Blocks)

BIBB	Description	Supported
DS-RP-A	Data Sharing - ReadProperty - A	✅
DS-RP-B	Data Sharing - ReadProperty - B	✅
DS-RPM-A	Data Sharing - ReadPropertyMultiple - A	✅
DS-RPM-B	Data Sharing - ReadPropertyMultiple - B	✅
DS-WP-A	Data Sharing - WriteProperty - A	✅
DS-WP-B	Data Sharing - WriteProperty - B	✅
DS-WPM-B	Data Sharing - WritePropertyMultiple - B	✅
AE-N-I-B	Alarm and Event - Notification Internal - B	✅
AE-ACK-B	Alarm and Event - ACK - B	✅
AE-INFO-B	Alarm and Event - Information - B	✅
AE-CRL-B	Alarm and Event - Recipient List - B	✅
SCHED-E-B	Scheduling - External - B	✅ (wiring verified; remote write not cross-instance wire-tested - see TUTORIAL.md)
T-VMT-I-B	Trending - Viewing and Modifying Trends - Internal - B	✅ (Trend Log Multiple; plain Trend Log has a known gap - see TUTORIAL.md)
T-ATR-B	Trending - Automated Trend Retrieval - B	✅ (via ReadRange on Trend Log Multiple)
DM-DDB-A	Device Management - Dynamic Device Binding - A	✅
DM-DDB-B	Device Management - Dynamic Device Binding - B	✅
DM-DOB-B	Device Management - Dynamic Object Binding - B	✅
DM-DCC-B	Device Management - Device Communication Control - B	✅
DM-TS-B / DM-UTC-B	Device Management - Time Synchronization / UTC - B	✅
DM-RD-B	Device Management - ReinitializeDevice - B	✅
DM-BR-B	Device Management - Backup and Restore - B	✅

Services (executed / B-side, unless noted)

Service	Notes
ReadProperty / ReadPropertyMultiple	Responds to property reads (DS-RP-B / DS-RPM-B).
WriteProperty / WritePropertyMultiple	Accepts writes to commandable outputs, Diamond, and Crimson's `Recipient_List` (DS-WP-B / DS-WPM-B).
WriteProperty (initiate)	Schedule 1 writes Chartreuse locally and a remote peer's Analog Output 1 (SCHED-E-B / DS-WP-A).
Who-Is / I-Am	Answers Who-Is with I-Am; broadcasts I-Am at start-up and on restart; also initiates Who-Is at start-up (DM-DDB-A,B).
Who-Has / I-Have	Answers Who-Has with I-Have (DM-DOB-B).
(Un)ConfirmedEventNotification	Sends alarm/event notifications for Diamond to Crimson's recipients (AE-N-I-B).
AcknowledgeAlarm	Accepts an acknowledgement for Diamond's alarm (AE-ACK-B).
GetEventInformation	Reports active events (AE-INFO-B).
DeviceCommunicationControl	Accepts `disable-initiation` / `enable`, optionally password-gated (DM-DCC-B).
ReinitializeDevice	Accepts COLDSTART/WARMSTART plus the five backup/restore states (DM-RD-B / DM-BR-B).
TimeSynchronization / UTCTimeSynchronization	Accepts a time sync request (DM-TS-B / DM-UTC-B).
AtomicReadFile / AtomicWriteFile	Reads and writes File 1 "Ivory" (DM-BR-B).
ReadRange	Retrieves `Log_Buffer` from a Trend Log / Trend Log Multiple (T-ATR-B). A plain ReadProperty of `Log_Buffer` is rejected.

Object types

Object type	Instance	Name
Device	389005	Rainbow
Analog Input	1	Bronze
Binary Input	1	Emerald
Multi-state Input	1	Hot Pink
Analog Output	1	Chartreuse
Binary Output	1	Fuchsia
Multi-state Output	1	Indigo
Analog Value	1	Diamond
Notification Class	1	Crimson
Network Port	1	Vermilion
Schedule	1	Saffron
Calendar	1	Cream
File	1	Ivory
Trend Log	1	Lilac
Trend Log Multiple	1	Magenta

Every required property of every object, and who answers it, is in docs/PICS.md.

Requires the CAS BACnet Stack (licensed product)

This example builds against the CAS BACnet Stack, which is a commercial Chipkin product - it is not free or open source, and there is no public/trial build. The stack is referenced here as the private git submodule submodules/cas-bacnet-stack; you can only fetch and build it once you have a CAS BACnet Stack license and access to that repository.

To get the CAS BACnet Stack (and access to build this example), contact Chipkin: https://store.chipkin.com/services/stacks/bacnet-stack or sales@chipkin.com.

You do not need a stack licence to read this example, or to run a prebuilt release binary. The licence is what lets you build it - that is the part the stack submodule gates.

What's in this repository

This is a self-contained project. It ships:

main.cpp - the example device.
common/ - the shared helper (UDP, callbacks, CLI, keyboard) vendored in.
CMakeLists.txt - the build, the same on Windows, Linux, and macOS.
docs/PICS.md - the conformance statement.
submodules/cas-bacnet-stack/ - the CAS BACnet Stack as a git submodule (private; requires a license - see above). Its sources are compiled into the executable, so there is no library or DLL to build, ship, or install.

Prerequisites

A C++17 compiler (MSVC, GCC, or Clang).
CMake >= 3.15.
Git (to fetch the stack submodule).

Windows

C++ compiler - install Visual Studio Community (free) and select the "Desktop development with C++" workload.
CMake - from https://cmake.org/download/, or winget install Kitware.CMake.

Linux / macOS

Debian/Ubuntu: sudo apt install build-essential cmake git
macOS: xcode-select --install and brew install cmake

Build

CMake only, and the same two commands on every platform:

git clone --recursive https://github.com/chipkin/BACnetProfileExample-B-BC-CPP.git
cd BACnetProfileExample-B-BC-CPP

cmake -B build -S .
cmake --build build --config Release

Already cloned without --recursive? Run git submodule update --init --recursive first - the build needs the stack submodule.

The first build takes a few minutes - it compiles the entire CAS BACnet Stack (~600 source files) into the executable. Rebuilds after that are incremental and take seconds.

If your CAS BACnet Stack lives somewhere other than the bundled submodule, point CMake at it: cmake -B build -S . -D CAS_STACK_DIR=/path/to/cas-bacnet-stack.

Run

# Linux / macOS
./build/BACnetExampleBBC

# Windows
.\build\Release\BACnetExampleBBC.exe

Expected output:

BACnet B-BC (Building Controller) Example - C++ v1.0.0
CAS BACnet Stack version: 6.0.21.0
Common helper (common/) version: 2.5.0
FYI: Listening for BACnet/IP on UDP port 47808 (Network Port 1).
TX 21 bytes to 192.168.3.255:47808 (broadcast) (Network Port 1)
FYI: Device 389005 ("Rainbow") ready. Vendor ID 389. Press 'h' for help.

The TX line is the start-up I-Am the device broadcasts to announce itself, to the local subnet broadcast address (computed from the Network Port's interface). As clients talk to the device you'll see RX ... bytes from ... and TX ... bytes to ... lines showing the traffic.

The device listens on UDP 47808 (BACnet/IP). Allow that port through your firewall. To use a different port, pass --port (see below).

A wall of red Error: lines at start-up is expected and is not your bug - it is the stack's own debug logging (the device hearing its own broadcast I-Am, a one-time BACnet/SC UUID notice, and - once trending starts - a continuous, non-fatal internal log flood, #2050). TUTORIAL.md explains all three.

Command-line options

Option	Default	Meaning
`--port <n>`	`47808`	UDP port to listen on (BACnet/IP).
`--deviceID <n>`	`389005`	The device's BACnet instance number (BACnet requires this to be configurable).
`--help`, `-h`	-	Show usage and exit.
`--version`	-	Print the example, stack, and `common/` helper versions, then exit.

Interactive commands

While the example runs, these keys are available:

Key	Action
`h`	Show the version information and this command list.
`q`	Quit.
up arrow	Increase Analog Input 1 (`Bronze`) by 1.1.
down arrow	Decrease Analog Input 1 (`Bronze`) by 1.1.
`s`	Add a Weekly_Schedule transition for Schedule 1 (`Saffron`) right now, so it can be observed without waiting for the wall clock.

Verify

With the CAS BACnet Explorer or any BACnet client:

Discover - Who-Is -> I-Am from 389005 (vendor 389). Verified live.
Object model - fifteen objects incl. Analog Value "Diamond", Notification Class "Crimson", Schedule "Saffron", Calendar "Cream", File "Ivory", Trend Log "Lilac" and Trend Log Multiple "Magenta". Object_List lists them all; Protocol_Revision = 26. Verified live.
Command an output (F-OUTPUTS) - WriteProperty Analog Output 1 (Chartreuse) Present_Value at a priority; read it back. Verified live.
Fire an alarm - WriteProperty Diamond Present_Value = 95; read Event_State (high-limit) and watch the EventNotification arrive. Write 50 to return to normal. Verified live.
Acknowledge / redirect (AE-ACK-B / AE-CRL-B) - AcknowledgeAlarm for Diamond; GetEventInformation; WriteProperty Crimson's Recipient_List with a new destination and confirm the next alarm goes there. Recipient_List read verified live; write not re-tested this session.
Trend (T-VMT-I-B / T-ATR-B) - wait a few seconds, then ReadRange Magenta's Log_Buffer; confirm Record_Count climbs and records decode. Verified live. (Lilac's own Record_Count stays 0 - see TUTORIAL.md.)
Backup (DM-BR-B) - AtomicWriteFile then AtomicReadFile against Ivory; round-trip the bytes; drive ReinitializeDevice through STARTBACKUP/ENDBACKUP. File_Size/Archive verified live; the AtomicFile round-trip and the ReinitializeDevice backup states were not re-tested this session.*
Device management - DeviceCommunicationControl disable-initiation / enable; ReinitializeDevice WARMSTART; TimeSynchronization - each accepted (not re-tested this session).

For a property-by-property review against the conformance statement, see TUTORIAL.md.

The BACnet profile example series

The CAS BACnet Stack supports every standardized device profile in ASHRAE 135-2024 Annex L, and there is one example repository per profile. Pick the profile your device claims, then the language you build in. "Ask" means the example hasn't been built yet for that language - contact Chipkin if you need one.

Controllers (Annex L.4)

Profile	C++	Node.js	C#	Rust	Python	Go
B-SS Smart Sensor	B-SS-CPP	B-SS-Node	B-SS-CS	B-SS-Rust	B-SS-Python	B-SS-Go
B-SA Smart Actuator	B-SA-CPP	Ask	Ask	Ask	Ask	Ask
B-ASC Application Specific Controller	B-ASC-CPP	B-ASC-Node	Ask	Ask	Ask	Ask
B-AAC Advanced Application Controller	B-AAC-CPP	Ask	Ask	Ask	Ask	Ask
B-BC Building Controller	B-BC-CPP	Ask	Ask	Ask	Ask	Ask

Life safety controllers (Annex L.5)

Profile	C++	Node.js	C#	Rust	Python	Go
B-LSC Life Safety Controller	B-LSC-CPP 🚧	Ask	Ask	Ask	Ask	Ask
B-ALSC Advanced Life Safety Controller	B-ALSC-CPP	Ask	Ask	Ask	Ask	Ask

Access control controllers (Annex L.6)

Profile	C++	Node.js	C#	Rust	Python	Go
B-ACC Access Control Controller	B-ACC-CPP	Ask	Ask	Ask	Ask	Ask
B-AACC Advanced Access Control Controller	B-AACC-CPP	Ask	Ask	Ask	Ask	Ask

Lighting controllers (Annex L.11)

Profile	C++	Node.js	C#	Rust	Python	Go
B-LD Lighting Device	B-LD-CPP	Ask	Ask	Ask	Ask	Ask
B-LS Lighting Supervisor	B-LS-CPP	Ask	Ask	Ask	Ask	Ask

Elevator controllers (Annex L.13)

Profile	C++	Node.js	C#	Rust	Python	Go
B-EM Elevator Monitor	B-EM-CPP	Ask	Ask	Ask	Ask	Ask
B-EC Elevator Controller	B-EC-CPP	Ask	Ask	Ask	Ask	Ask
B-AEC Advanced Elevator Controller	B-AEC-CPP	Ask	Ask	Ask	Ask	Ask

Authentication and authorization (Annex L.14)

Profile	C++	Node.js	C#	Rust	Python	Go
B-AS Authorization Server	B-AS-CPP	Ask	Ask	Ask	Ask	Ask

Miscellaneous (Annex L.7, combinable with any one family)

Profile	C++	Node.js	C#	Rust	Python	Go
B-BBMD Broadcast Management Device	B-BBMD-CPP	Ask	Ask	Ask	Ask	Ask
B-ACDC Access Control Door Controller	B-ACDC-CPP	Ask	Ask	Ask	Ask	Ask
B-ACCR Access Control Credential Reader	B-ACCR-CPP	Ask	Ask	Ask	Ask	Ask
B-RTR Router	B-RTR-CPP	Ask	Ask	Ask	Ask	Ask
B-GW Gateway	B-GW-CPP	Ask	Ask	Ask	Ask	Ask
B-DAP Device Address Proxy	B-DAP-CPP	Ask	Ask	Ask	Ask	Ask
B-SCHUB BACnet/SC Hub	B-SCHUB-CPP	Ask	Ask	Ask	Ask	Ask
B-GENERAL General device (Annex L.8)	(satisfied by every example above)	—	—	—	—	—

Operator interfaces and workstations (Annex L.1–L.3, L.9–L.10, L.12)

Client-side profiles.

Profile	C++	Node.js	C#	Rust	Python	Go
B-OD Operator Display	B-OD-CPP	Ask	Ask	Ask	Ask	Ask
B-OWS Operator Workstation	planned	—	—	—	—	—
B-AWS Advanced Operator Workstation	planned	—	—	—	—	—
B-XAWS Extended Advanced Operator Workstation	planned	—	—	—	—	—
B-LSAP Life Safety Annunciator Panel	planned	—	—	—	—	—
B-LSWS Life Safety Workstation	planned	—	—	—	—	—
B-ALSWS Advanced Life Safety Workstation	planned	—	—	—	—	—
B-ACSD Access Control Security Display	planned	—	—	—	—	—
B-ACWS Access Control Workstation	planned	—	—	—	—	—
B-AACWS Advanced Access Control Workstation	planned	—	—	—	—	—
B-LOD Lighting Operator Display	planned	—	—	—	—	—
B-ALWS Advanced Lighting Workstation	planned	—	—	—	—	—
B-LCS Lighting Control Station	planned	—	—	—	—	—
B-ALCS Advanced Lighting Control Station	planned	—	—	—	—	—
B-ED Elevator Display	planned	—	—	—	—	—
B-EWS Elevator Workstation	planned	—	—	—	—	—
B-AEWS Advanced Elevator Workstation	planned	—	—	—	—	—

🚧 = in progress. "Ask" = not yet built for that language; contact Chipkin if you need it. Profile definitions: ANSI/ASHRAE 135-2024 Annex L. BIBB definitions: Annex K. Get the stack: https://store.chipkin.com/services/stacks/bacnet-stack.

References

ANSI/ASHRAE Standard 135 (BACnet) - the protocol standard. Object model (Clause 12), alarming/events (Clause 13), trending (Clause 12.25/12.29), services (Clause 15/16), device profiles (Annex L).
What is BACnet? - Chipkin's introduction: https://docs.chipkin.com/protocols/bacnet/.
CAS BACnet Stack - product page and documentation: https://store.chipkin.com/services/stacks/bacnet-stack.
CAS BACnet Explorer - client for testing this device: https://store.chipkin.com/products/tools/cas-bacnet-explorer.
Shared helper used by this example - common/README.md.

See also TUTORIAL.md, docs/PICS.md, TODO.md, CHANGELOG.md, and AGENTS.md.

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BACnet B-BC (Building Controller) - C++ example

What is a B-BC (Building Controller) profile?

The device this example creates

What this example supports

BIBBs (BACnet Interoperability Building Blocks)

Services (executed / B-side, unless noted)

Object types

Requires the CAS BACnet Stack (licensed product)

What's in this repository

Prerequisites

Windows

Linux / macOS

Build

Run

Command-line options

Interactive commands

Verify

The BACnet profile example series

Controllers (Annex L.4)

Life safety controllers (Annex L.5)

Access control controllers (Annex L.6)

Lighting controllers (Annex L.11)

Elevator controllers (Annex L.13)

Authentication and authorization (Annex L.14)

Miscellaneous (Annex L.7, combinable with any one family)

Operator interfaces and workstations (Annex L.1–L.3, L.9–L.10, L.12)

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Name		Name	Last commit message	Last commit date
.github/workflows		.github/workflows
common		common
docs		docs
submodules		submodules
.gitignore		.gitignore
.gitmodules		.gitmodules
AGENTS.md		AGENTS.md
CHANGELOG.md		CHANGELOG.md
CMakeLists.txt		CMakeLists.txt
LICENSE		LICENSE
README.md		README.md
TODO.md		TODO.md
TUTORIAL.md		TUTORIAL.md
main.cpp		main.cpp

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BACnet B-BC (Building Controller) - C++ example

What is a B-BC (Building Controller) profile?

The device this example creates

What this example supports

BIBBs (BACnet Interoperability Building Blocks)

Services (executed / B-side, unless noted)

Object types

Requires the CAS BACnet Stack (licensed product)

What's in this repository

Prerequisites

Windows

Linux / macOS

Build

Run

Command-line options

Interactive commands

Verify

The BACnet profile example series

Controllers (Annex L.4)

Life safety controllers (Annex L.5)

Access control controllers (Annex L.6)

Lighting controllers (Annex L.11)

Elevator controllers (Annex L.13)

Authentication and authorization (Annex L.14)

Miscellaneous (Annex L.7, combinable with any one family)

Operator interfaces and workstations (Annex L.1–L.3, L.9–L.10, L.12)

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