Description
The Beckhoff KL6904 is a TwinSAFE logic Bus Terminal that integrates communication and safety logic with four digital safety outputs. Operating at 24 V DC with 0.5 A per channel, it enables the configuration of certified safety functions such as emergency stop or safety door monitoring within EtherCAT and TwinSAFE systems.
Technical Specifications
| Condition |
New/Never Used Surplus |
| Brand |
Beckhoff |
| Category |
Industrial Automation |
| Part Number |
KL6904 |
| Subcategory |
TwinSAFE Logic Terminal |
| Function |
Communication interface and 4-port safe digital output terminal |
| Protocol |
TwinSAFE / Safety over EtherCAT |
| Connection Technology |
2-wire |
| Specification |
Link unit between safe input and output signals |
| Number of Outputs |
4 safe digital outputs |
| Output Current |
Max. 0.5 A (per channel), min. 20 mA |
| Supply Voltage |
24 V DC |
| Cycle Time |
4…100 ms (configurable) |
| Fault Response Time |
≤ watchdog time (parameterizable) |
| Safety Standards |
EN ISO 13849-1:2008 (Cat. 4, PL e), EN 61508:2010 (SIL 3) |
| TwinSAFE Connections |
Up to 15 safe connections |
| TwinSAFE Groups |
Up to 8 groups |
| Function Blocks |
Up to 48 configurable safety logic blocks |
| Communication Interfaces |
Via fieldbus using TwinCAT System Manager |
| K-bus Current Consumption |
Max. 250 mA |
| Power Contact Current |
Load-dependent |
| Installation Position |
Horizontal |
| Electrical Isolation |
Between field and logic circuits |
| Weight |
Approx. 100 g |
| Operating Temperature |
0°C to +55°C |
| Storage Temperature |
-25°C to +85°C |
| Relative Humidity |
95%, non-condensing |
| Protection Class |
IP20 |
Information About KL6904
The KL6904 is part of Beckhoff’s TwinSAFE series, providing integrated safety control directly within the Bus Terminal I/O system. Designed for use in safety-critical automation applications, it combines communication, logic, and safe output control in one module. It allows configuration of up to 15 TwinSAFE connections, 48 function blocks, and 8 TwinSAFE groups for flexible safety programming. Typical applications include implementing emergency stop circuits, guard door monitoring, and two-hand control systems. The logic is configured through the TwinCAT System Manager and downloaded via the fieldbus, enabling centralized control without additional safety controllers. Its four safe digital outputs allow direct connection to actuators, simplifying wiring and reducing hardware requirements. With certifications up to SIL 3 (IEC 61508) and PL e (ISO 13849), the KL6904 ensures high functional safety, reliability, and easy integration into existing EtherCAT and Safety-over-EtherCAT systems.
Key Features:
- Integrated TwinSAFE Logic: Combines safety logic, communication, and output control within a single Bus Terminal module for simplified system design.
- Configurable Safety Functions: Supports up to 48 certified safety function blocks such as emergency stop, two-hand control, and safety gate monitoring.
- High Safety Compliance: Certified to SIL 3 (EN 61508) and PL e (ISO 13849-1, Cat. 4) for demanding industrial safety applications.
- Flexible Communication: Operates via Safety over EtherCAT, enabling reliable data exchange with other TwinSAFE devices across the network.
- Four Safe Outputs: Provides four individually monitored outputs rated at 0.5 A each, suitable for direct control of safety actuators.
- Scalable Safety Architecture: Allows up to 15 TwinSAFE connections and 8 groups, supporting decentralized and modular system layouts.
- Adjustable Cycle Time: Configurable response time between 4 and 100 ms for adapting to various safety and performance requirements.
- Easy Configuration via TwinCAT: Safety parameters, logic, and function blocks are configured through the TwinCAT System Manager for user-friendly setup.
- Compact and Robust Design: Slim IP20 housing optimized for control cabinet installation with reliable horizontal mounting.
- Comprehensive Fault Monitoring: Detects wire breaks, communication faults, and configuration errors to maintain system integrity.
The KL6904 delivers the reliability and precision required for advanced functional safety, providing modular, software-configurable protection for machinery and automation systems.
Damage 
Loss 
Theft 
