BK5110 by Beckhoff

The BK5110 is a fieldbus coupler produced by Beckhoff as part of the BK EtherCAT Bus Couplers series. It forms the gateway between an EtherCAT trunk line and the local terminal segment, transferring distributed process data to the controller in real time. By consolidating I/O connections in a compact rail-mounted device, the coupler simplifies wiring in industrial automation cells and provides deterministic network timing without separate repeater modules. This arrangement allows distributed sensors and actuators to communicate with the central controller through a single network connection.

The coupler can scan up to 256 digital I/O channels over the K-bus. Its housing measures 50 × 100 × 68 mm, allowing it to fit into space-constrained control cabinets. The supply section accepts a single 24 VDC feed, which also supplies the power contacts used to energize subsequent terminals. Each power contact can carry up to 10 A, supporting connected loads such as solenoid valves and relay coils. For cabinet installation, the housing clips onto a 35 mm DIN rail, while a five-pole open-style connector provides the fieldbus connection. Internally, a 5 V supply rated at 500 mA powers the K-bus, and the input stage remains within its steady-state current limit during normal operation.

The enclosure has an IP20 rating, providing protection against accidental contact with the terminals when the coupler is installed in a suitable control cabinet. A starting inrush of 2.5 times the continuous current is permitted, after which current consumption stabilizes below the system-supply maximum of 200 mA. Up to 64 Beckhoff Bus Terminals can be connected to the coupler, allowing the local terminal segment to accommodate a range of digital devices. Process data are arranged into 5 receive and 5 transmit PDO slots, keeping cyclic EtherCAT telegrams compact during controller communication. The head station has no built-in analog channels, so any required analog signal conditioning is handled by compatible terminals attached to the local bus segment.