Bridging a proprietary lighting and shading bus to BACnet/IP, on a DIN-rail ESP32

The challenge

The manufacturer’s lighting and shading modules talk to each other on their own bus. That works inside the room, but a building automation system cannot see any of it, so lighting and blinds stay out of schedules, occupancy logic and the operator’s screens.

Rewriting every module for BACnet was not the answer. The manufacturer needed one small device on the DIN rail that listens to its bus and presents what it hears as BACnet objects on the building network.

Why the CAS BACnet Stack

• The stack runs on the ESP32, the same low-cost Wi-Fi and Ethernet capable microcontroller the device was built on, using the embedded build target so only BACnet/IP and the needed objects are compiled in.
• Many virtual devices in one process means a bridge can present each module, or each room, as its own BACnet device if that suits the site.
• Source is included, royalty-free, and supported by the engineers who maintain it.

The solution

The DIN-rail device reads and writes the proprietary bus, and the CAS BACnet Stack publishes what it knows as a BACnet/IP server. When the building system reads or commands a module, the stack calls back into the bridge, which carries the request onto the bus.

The manufacturer’s modules are unchanged. BACnet lives in the bridge.

Results

• Building automation systems see and control the lighting and shading modules over BACnet/IP.
• Existing modules join the building system through one DIN-rail device.