Product Description:

The KL6904-0001 is a safety I/O terminal manufactured by Beckhoff. Intended for industrial automation, it provides fail-safe digital switching that can be evaluated by a TwinSAFE logic controller through Safety over EtherCAT. Mounted alongside standard bus couplers, the device allows safety functions such as emergency stop chains and guard door monitoring to use the same general wiring arrangement as process control signals. This makes it suitable for compact machine sections where safety and standard control signals must coexist in the same terminal row without separate relay modules. Because the terminal integrates into a bus terminal system, it can be placed close to related I/O points to reduce field wiring complexity.

It operates from a field supply of 24 V DC, and its backplane draws up to 250 mA from the K-bus to power internal logic. Each safe output can source up to 0.5 A, and installation uses 2-wire connection technology with direct latching onto a 35 mm DIN rail. The spring-contact terminals support secure conductor retention during normal machine vibration. Its narrow housing helps preserve rail space in dense control cabinets, and the enclosure is rated IP20 for finger-safe use in ventilated panels. Cyclic data and status bits are exchanged over the TwinSAFE and Safety over EtherCAT communication path.

Up to 48 user-selectable TwinSAFE function blocks can be instantiated, and the terminal can participate in as many as 8 independent TwinSAFE groups for segmented machine zones. That grouping structure helps isolate separate safety zones so one protected area can be evaluated without forcing unrelated sections of the machine into the same response. A total of 4 safety-rated output channels is available, and the common power pin can conduct up to 10 A so inductive loads such as contactors can be switched directly. The terminal also permits up to 15 safe connections, which provides room for upstream sensors or peer outputs without requiring separate external relays.