BK1250 | BECKHOFF | Compact EtherCAT to K-Bus Terminal Coupler

Product Overview

The BK1250 (BK1250) is a specialized "Bus Coupler in a terminal housing" designed to function as a bridge between the high-speed EtherCAT (E-bus) system and the standard Bus Terminal (K-bus) system. Engineered for seamless system integration, the BK1250 allows users to mix EtherCAT Terminals (ELxxxx) and standard Bus Terminals (KLxxxx) within the same terminal strand. This is particularly valuable for retrofitting existing installations or expanding systems where specialized K-bus modules are required alongside a modern EtherCAT infrastructure. By converting the EtherCAT protocol to the K-bus internal signal representation, the BK1250 enables the control of up to 64 standard Bus Terminals (expandable to 255) while maintaining the deterministic performance and diagnostic advantages of the EtherCAT network.

Technical Configuration

The BK1250 hardware architecture acts as a gateway that is physically integrated into the EtherCAT terminal block via E-bus contacts. It manages the process data exchange for up to 1024 bytes of input and 1024 bytes of output, supporting a massive density of 8,192 digital I/O points or 256 analog signals. The coupler features an internal 500 mA K-bus power supply to energize the logic of the attached Bus Terminals. Configuration is highly flexible, allowing engineers to set up the module via the KS2000 software or directly through EtherCAT using ADS (Automation Device Specification) commands. The compact 12 mm housing includes signal LEDs for real-time status monitoring of power, K-bus communication, and EtherCAT link activity.

Technical Specifications

Technical FAQs

Can I place the BK1250 anywhere in an EtherCAT terminal strand?

Yes, the BK1250 is designed to be installed as a standard terminal within an EtherCAT block. It bridges the communication from that point forward to any following KLxxxx (K-bus) terminals.

What happens if the total current draw of my K-bus terminals exceeds 500 mA?

The BK1250 provides 500 mA for the K-bus logic. If your terminal configuration requires more current, you must insert a KL9400 or KL9410 power supply terminal into the K-bus segment to refresh the logic power.

Is software configuration required to recognize the attached Bus Terminals?

The BK1250 automatically scans the attached K-bus terminals upon startup. However, in the TwinCAT System Manager, you must manually append the KL terminals to the BK1250 device to define the process image mapping correctly.

Engineering & Installation Guide

• System Migration Strategy: Use the BK1250 to leverage your existing inventory of KL-series terminals while upgrading your main controller to an EtherCAT-capable Embedded PC. This approach significantly reduces hardware costs and wiring labor during system overhauls.

• Power Contact Management: The coupler passes through the 24 VDC power contacts (up to 10 A). Ensure that the power supply connected to the BK1250 is sufficient for both the K-bus logic and the field power requirements of the attached digital/analog modules.

• Wiring Precision: The module features spring-actuation terminals. For high-vibration industrial environments, always use ferrules for stranded wires (0.14 to 1.5 mm²) to ensure a gas-tight connection. A stripping length of 8 to 9 mm is required to prevent contact issues or internal short circuits.

• K-Bus Extension: For large-scale applications requiring more than 64 terminals, utilize K-bus extension terminals (KL9020/KL9050) in conjunction with the BK1250 to manage up to the maximum limit of 255 modules.