In addition to BACnet/IP, Beckhoff now also supports BACnet MS/TP (Master Slave/Token Passing) with the EL6861 EtherCAT Terminal. This serial interface can be used to directly control and monitor BACnet-compatible field devices, such as pumps, drives, frequency converters or similar, as sub-bus systems, without the need for additional gateways or routers. Up to 64 devices with RS485 low power transceivers can be connected. In addition, several terminals can be operated in parallel to scale the number of MS/TP channels that can be supported.
Using the 1-channel BACnet MS/TP interface, hardware and engineering costs can be significantly reduced since configuration is performed centrally in the TwinCAT System Manager and external devices, such as routers or gateways, do not need to be connected. Combined with the BACnet MS/TP driver integrated within TwinCAT automation software, the terminal implements the BACnet protocol in compliance with Revision 12. The terminal can also be used locally without routing to the BACnet/IP network.
The RS485 interface guarantees high interference immunity through electrically isolated signal transmission. The EL6861 provides 1 x 5 V DC at 20 mA (electrically isolated, short-circuit-proof) from the E-bus supply for use with the bias resistors (network bias).