Beckhoff EL1904 4-Channel Digital Input Terminal

Beckhoff EL1904 TwinSAFE EtherCAT terminal provides four digital safety inputs for 24 V DC sensors in a single module, making it well suited for safety-related interlocks, safety gates, and emergency-stop chains in automated systems. Each of the four channels uses floating (potential-free) contacts and is individually monitored, with a dedicated LED per channel to indicate status. As part of Beckhoff’s EtherCAT Bus Terminal lineup, the EL1904 communicates safety data over the TwinSAFE bus (E-bus), enabling safe, fail-safe I/O on the same network as standard I/O. When configured as a two-channel safety path, this module meets IEC 61508:2010 SIL 3 requirements and is classified Cat 4, PL e for robust safety architectures. The terminal exposes eight connection points for four inputs (Input 1+, Input 1−, Input 2+, Input 2−, Input 3+, Input 3−, Input 4+, Input 4−), with typical power dissipation around 1 W and per-input status indicators. It is designed to interface with common 24 V DC safety devices such as interlocks and E-stop devices and integrates with TwinCAT software for real-time monitoring, diagnostics, and safety logic execution. This EL1904 module is suitable for decentralised safety applications within Beckhoff automation systems, enabling compact, reliable safety input conditioning without a separate safety controller.