BK5151 by Beckhoff

The BK5151 EtherCAT coupler is produced by Beckhoff within the BK EtherCAT Bus Couplers series. It connects a segment of modular Bus Terminals to an EtherCAT network, translating local I/O signals into the cyclic process image used by the master controller. By combining protocol conversion, power injection, and address management in a compact form factor, it streamlines cabinet layouts. The coupler occupies only 44 mm of rail width, so it can be mounted immediately beside PLC or motion modules without consuming excessive enclosure space.

A digital capacity of 960 inputs/outputs is available when the coupler is fully populated with terminal slices, while mixed-signal stations can carry 60 inputs/outputs of analog data. Frames are exchanged across the EtherCAT line at a maximum rate of 1,000 kbaud, and each scan delivers up to 16 Rx / 16 Tx PDOs, giving deterministic access to process variables. The upstream link is established through a 9-pin D-Sub plug, and the bus logic draws only 320 mA from the internal 24 V supply, leaving reserve power for field devices. The nominal operating voltage is 24 VDC, and the contact system can forward the same potential to every downstream terminal. Compliance with the EN 60715 standard for 35 mm rail profiles permits snap-in installation without additional brackets.

Up to 64 bus terminals can be chained after the coupler before another power feed is required. The enclosure measures 44 × 100 × 68 mm, making it suitable for standard cabinet depths, and the housing carries an IP20 protection rating for dry, enclosed locations. Both the internal backup fuse and the power contacts are rated at 10 A, so distributed loads such as solenoid banks can be energized directly through the feed-through conductors. The power contacts support a maximum voltage of 24 VDC. The detachable module foot clips securely onto the rail to reduce movement caused by vibration during machine operation.