BACnet Guide

The building automation market continues to grow steadily, and with it the number of suppliers in this sector. Whereas in the past the planning, execution and maintenance of building automation was left to just a few large standard companies, it is now increasingly common to plan and tender independently of manufacturers and to award the building automation trade to local plant engineers as system integrators.

To ensure interoperable and manufacturer-independent communication between the various trades, the American Society of Heating, Refrigerating and
Air-Conditioning Engineers (ASHRAE) developed a standardized network protocol.

BACnet (Building Automation and Control Networks) not only ensures interoperability between devices from different manufacturers, but also offers several advantages in the practical use of management and control equipment (BMS systems).

The most important difference to other protocols: BACnet is object-oriented. This means that a BACnet object contains all the information that belongs to the functionality of a data point.

While other protocols such as KNX or ModBus only specify the existing value (Present Value) as a data point, BACnet provides several additional pieces of information (so-called "properties") in a single object. For example, information on maximum values (High Limit), minimum values (Low Limit), alarm identification (Notify Type), change threshold (COV Increment) and many more.

While other protocols only provide the ACTUAL value as the only information, which then still has to be interpreted in the management and operating equipment, the management function of BACnet takes over the interpretation and evaluation of the information directly in the automation station. This avoids misinterpretations and saves valuable time.

All BACnet objects and information are stored and processed decentrally in the automation station. Since this also includes the execution of schedules or the generation of alarms, these are reliably executed even when the MBE system is offline. BACnet thus offers significantly increased operational reliability.

The objects and their properties can be easily read out from the network at any time using various tools. This means that all information is immediately available to the user and does not have to be requested from the programmers in a time-consuming process.

Since each BACnet object contains all information about the data point, including the description, it makes sense in the context of a BIM approach to select this description according to the asset identification system of the building automation system. Based on this approach, the operating and management functions required for a specific project can be implemented with significantly reduced effort. In B-CON, for example, operating elements (controls) are available for all relevant BACnet objects.
The integrated schedule management allows the simple administration of time schedules in the automation systems as well as the configuration of the time switch. Trends are not simply displayed, but recorded, created in the trend management and archived for a long time.

BACnet is currently the ideal protocol at the management level (MBE / GLT) and offers numerous advantages in practical use for building owners, investors, planners and building operators. However, there are also some important things to consider. Since the use of BACnet involves a shift of intelligence from the MBE to the automation station, somewhat
more planning and significantly more specifications and definitions are required in advance.