System overview BACnet

TwinCAT BACnet allows users to access all BACnet objects and their properties from the PLC and the visualization, i.e., users can observe and change the state of these objects. Ready-made PLC function blocks reduce the programming effort to a minimum. Beckhoff offers unrivalled flexibility through its finely scaled product range: users have a choice between controllers for several hundred to several thousand BACnet objects, which enables them to configure tailor-made solutions for their application in terms of performance and costs.

Beckhoff controls support the BACnet Building Controller Profile (B-BC). In addition to the server application, TwinCAT BACnet offers extensive client functions that enable efficient communication with other BACnet devices and ensure maximum flexibility for the user. The biggest advantage of TwinCAT BACnet is the automatic generation of BACnet objects: in systems with a few thousand BACnet objects, creating a BACnet project from the PLC results in enormous time savings, and the costs for project creation and configuration are minimized.

The DIN rail-mountable CX8191, CX9020, CX51xx, and CX52xx Embedded PCs, the Industrial PCs from the C60xx series, and panel PCs with different display sizes are certified according to the BACnet standard ISO 16484-5 Protocol Revision 1.14 and offer a control platform for integrated and manufacturer-spanning building automation that is precisely scalable in terms of performance. Numerous additional functions have been implemented that extend beyond the requirements for BACnet building controllers. Thanks to the integration of the BACnet protocol in the TwinCAT System Manager, it is possible to efficiently configure the I/O Bus Terminals and the BACnet devices with a single tool. BACnet servers and clients can be structured from the PLC; access to the BACnet properties takes place directly from the PLC. This makes the process user-friendly and shortens the development time.

Extensive additional functions supplement the required interoperability function blocks of the Beckhoff B-BC devices. Support for the character sets UTF-8, JIS0208, UCS-4/-2, and ISO 8859-1 enables TwinCAT BACnet to be used worldwide. Other functions include the dynamic creation of BACnet objects, which allows the subsequent creation and configuration of schedules and trend objects, among other things. Distributed clocks can be synchronized with the aid of the supported client and master functions. BBMD (BACnet Broadcast Management Device) services have been integrated into TwinCAT BACnet/IP for use in widely distributed networks. Integrating spatially remote and third-party devices is particularly straightforward within the framework of the client functionality. BACnet networks can be searched easily. Devices available in the network can then be transferred to the project planning as clients at the push of a button. Support for the EDE format (Engineering Data Exchange) facilitates automatic documentation of the project planning for a Beckhoff controller. The EDE file generated by TwinCAT BACnet can then be transferred to other project participants, e.g., the building management system installer, for further processing. Field devices can be connected to BACnet/IP via serial BACnet networks using the EL6861 EtherCAT Terminal. In addition, the BACnet routing function between IP and MS/TP has been certified. There is no limit on the number of possible sub-buses via the EL6861 Terminals, so that several fieldbuses can be connected to a single automation station with optional routing. This leads to significant cost savings compared to systems in which many automation stations have to be used for this purpose. TwinCAT BACnet also features extensive diagnostic functions, which make the analysis of BACnet communication easier for the system integrator.