BK1250 by Beckhoff

The BK1250 is a bus coupler produced by Beckhoff in the BK EtherCAT Bus Couplers series. The unit links an EtherCAT network to Beckhoff's K-bus I/O system so that PLCs can address discrete and analog points distributed along the rail. By converting protocol frames in hardware, it removes the need for additional gateways and keeps cycle times short. The coupler fastens to a 35 mm DIN rail beside standard Bus Terminals, giving machine builders a compact means of aggregating high-density signals inside control cabinets.

Up to 8192 digital I/O channels can be streamed through the device, a capacity matched to large material-handling or packaging lines. For analog measurement, the internal bus accommodates 256 analog I/O points so temperature, pressure, or position data reaches the controller in the same frame. A stack of 64 Bus Terminals may be connected, with each terminal powered and addressed through integrated K-bus contacts. The EtherCAT interface sustains a deterministic 100 Mbit/s data rate, allowing submillisecond update times when the network topology is optimized. System electronics draw a maximum of 200 mA from the upstream 24 V supply, which simplifies power budgeting for compact PLC enclosures.

The coupler isolates its field side from the logic electronics with a dielectric strength of 500 V, reducing the risk of cross-domain faults under transient conditions. Power distribution to downstream terminals is rated for 10 A per contact at up to 24 V DC, so actuators can be driven directly without extra feed modules. A polycarbonate housing shields the circuitry while keeping the overall weight low. Once mounted, the coupler attains an IP20 protection rating, making it suitable for installation in closed electrical cabinets. Spring-actuated wiring clamps accelerate field termination, and the internal K-bus can source up to 500 mA for electronics on the connected terminals.