The whole C-Bus is treated as a one BACnet device. From the client side you can update the BACnet device properties Name and Description. All other device properties are currently read-only. This can be changed in future releases.

C-Bus data points are exported as BACnet value objects. Analog C-Bus points are mapped as BACnet Analog Value (AV) objects, digital C-Bus points are mapped as Digital Value (DV) objects. There is no special mapping for Input and Output points. All BACnet points are commandable. However, only the priority 8 (manual-operator) is allowed to write a new present-value. This can be changed in the BACnet preferences, see the parameter Manual level. BACnet points support COV subscription.

C-Bus Attributes and BAcnet Object Properties

While C-Bus data points are comparable to BACnet point objects, C-Bus point attributes correlate to BACnet point properties. The following table shows the mapping of essential attributes between C-Bus and BACnet. These attributes are discovered while commissioning the gateway and periodically refreshed in runtime.

Writing Point Value

To override the point value, you need to write the new value to the commandable level. Default level is 8 and can be changed in the BACnet preferences. When written, the gateway switches the C-Bus point mode into Manual and writes the new C-Bus point value.

To return to Auto mode, you need to write a NULL value to the commandable level. When written, the gateway switches the C-Bus point mode into Auto.

Time Synchronization

The gateway uses BACnet protocol to synchronize the date/time between the central building automation system and the C-Bus controllers. The BACnet service UTCTimeSynchronization sets the time in all controllers where the BACnet mapping is enabled. Controllers not enabled for BACnet export are not synchronized.