Product Description:

The EL1904 safety input terminal is produced by Beckhoff as part of the EL EtherCAT Terminals series. It accepts four dry-contact or electronic sensor channels and transmits their state through the TwinSAFE protocol embedded in Safety over EtherCAT. In an industrial automation cell, the module allows emergency-stop buttons, guard switches, or light curtains to be monitored directly on the bus, eliminating separate safety wiring while still providing certified performance for functional safety tasks.

The terminal is powered from 24 V DC, which feeds both the internal electronics and the connected sensors. It offers 4 safety inputs, enabling individual channel diagnostics and time stamping for each signal edge. Reaction to a change of state is completed within 4 ms, so safety logic can interrupt power before hazardous motion exceeds permissible limits. For synchronizing distributed modules, the clock output can source 15 mA maximum, which is suitable for driving optocouplers. The input and output process images each occupy 6 bytes, giving the controller status bits, toggling counters, and time stamps without taxing network bandwidth. Module housing dimensions of 12 × 100 × 68 mm match all 12 mm wide EtherCAT slices, maintaining spacing inside control enclosures.

Functional reliability is certified to PL e, and the calculated probability of dangerous failure per hour is 1.11E-09, supporting applications that demand the highest risk reduction. A dielectric strength of ≥500 V DC isolates the logic circuitry from neighboring power segments, while the overvoltage category II rating clarifies expected transient levels on the supply. The terminal operates in protection class III circuits and carries an enclosure rating of IP20, so it is intended for installation inside a control cabinet. The terminal supports distributed safety concepts in which deterministic I/O nodes shorten wiring runs while maintaining system integrity.