Product Description:

The BK4000 is an EtherCAT bus coupler produced by Beckhoff as part of the BK EtherCAT Bus Couplers series. Designed for distributed control systems, the device converts EtherCAT frames into the local K-bus format used by Beckhoff I/O terminals. This conversion lets a central PLC access mixed-signal terminals mounted directly beside the coupler, making the unit a compact network interface for machine and process automation. It occupies one slot on the DIN rail and supplies both communication and power lines to the attached terminals.

The coupler operates from a 24 V DC supply that powers its internal electronics and the adjoining terminal stack. Each power contact can carry up to 10 A, so actuators and sensor groups connected through the I/O modules can draw current without an auxiliary distributor. A single node supports up to 64 Bus Terminals, providing room to combine digital switching, analog measurement, and specialty modules on one EtherCAT address. For analog channels, the process image reserves 2 bytes per channel, and these words are transmitted as signed integer values, allowing the PLC to interpret signed bipolar signals without conversion tables.

Configuration is performed through the front-mounted RS-232 interface, which accepts simple text commands for address assignment and baud rate setup. Field wiring enters the stack through spring-loaded terminals that provide vibration-resistant clamping and support efficient wiring during service. The enclosure measures 50 × 100 × 68 mm, so multiple couplers can share a compact control cabinet while leaving room for adjacent terminal groups and cable routing. Installation on a 35 mm EN 60715 rail requires only a vertical snap, and the integrated K-bus extender allows as many as 255 additional terminals to be added while maintaining common power distribution and consistent process-data timing.