Beckhoff KL6011 Bus Terminal Serial Interface

Description

Integrating serial communication directly into the Beckhoff I/O system, the Beckhoff KL6011 serial interface terminal enables connection to devices equipped with a 20 mA current loop (TTY) interface. The terminal operates fully independently of the higher-level bus system, executing bidirectional transmission of data channels (TxD and RxD) in full duplex mode. The active or passive status of the current loop can be established through external wiring configurations, ensuring high adaptability to legacy serial interfaces, industrial weighing systems, and long-distance terminal connections up to 1000 meters.

Features

• Active/Passive Flexibility: Configurable 2 x 20 mA active or passive current loops to interface with various sender/receiver architectures.
• Configurable Baud Rates: Supports transfer rates ranging from 1200 baud up to 19,200 baud to match legacy serial peripherals.
• Integrated Data Buffering: Equipped with a 128-byte receive buffer and a 16-byte transmit buffer to handle temporary data peaks without processing loss.
• K-Bus Galvanic Isolation: Provides robust 500 V electrical isolation between the internal K-bus and the field-side signal paths to safeguard control networks.
• Variable Process Image: Flexible bit-width configuration in the process image (from 3 x 8-bit to 5 x 8-bit user data plus control/status byte).

Applications

• Legacy Peripheral Integration: Connecting older industrial printers, barcode readers, and display terminals to modern EtherCAT/K-bus architectures.
• Industrial Weighing Systems: Direct communication with load cells and digital balances that rely on 20 mA current loops.
• Long-Distance Serial Links: Point-to-point serial communication up to 1000 meters in high-noise environments where RS232 is ineffective.

Technical Specifications

Connections and Interfaces

Empirical Engineering Insights

Alternative Models & Compatibility

For applications requiring pluggable wiring terminal structures, the KS6011 represents the direct functional alternative, retaining the exact same internal logic and register mapping. If your infrastructure utilizes RS485 or RS232 protocols rather than 20 mA current loops, migrate to the KL6021 or KL6001 terminals, respectively, as the KL6011 electrical physical layer is restricted strictly to TTY communication.

Application Pitfalls & Engineering Notes

A frequent commissioning failure involves improper active/passive configuration of the 20 mA current loop. Because a TTY loop requires exactly one current source to function, placing two active devices on the same loop will cause hardware damage or component burnout due to overcurrent. Ensure that if the connected external device is active (supplying the loop current), the KL6011 is wired strictly in its passive configuration (avoiding terminals 3 and 7).

Commissioning & Wiring Tips

To optimize transmission reliability up to the 1000 m limit, use low-capacitance, shielded twisted-pair (STP) cabling. Connect the shield on one end only—ideally at the Bus Coupler ground rail—to prevent ground loops. Note that configuration of the data format (baud rate, parity, stop bits) is managed dynamically via the terminal registers using TwinCAT or alternative coupler configuration software, requiring no physical dip-switch adjustments on the hardware block.

Installation Guidelines