EL1899 by Beckhoff

Beckhoff's EL1899 is a digital input module in the EL EtherCAT Terminals series. The unit captures field-level switch states and transmits them to a controller over the EtherCAT bus, enabling deterministic updates for machinery and process equipment. It connects beside power-feed terminals and other I/O slices to form compact nodes near the machine. Its design allows input hardware to be positioned close to sensors, reducing cabinet wiring while maintaining signal integrity in low-voltage automation circuits.

The terminal accepts a nominal control supply of 24 V DC from the positive feed distributed by the adjacent power contacts. Incoming signals pass through an input filter of 10 µs, which suppresses contact bounce while preserving fast signal edges. The housing locks onto a 35 mm DIN rail, and field wiring uses direct plug-in spring cages for solid or flexible conductors. When installed inside a suitable enclosure, the assembly provides an IP20 protection rating that prevents accidental contact with hazardous internal parts. The electronics receive operating current via the power contacts, eliminating the need for an additional supply connection on the front of the terminal. This arrangement also allows the module to share the distributed control supply with neighboring terminals in the I/O node.

The module maps its digital input channels to 16 input bits in the EtherCAT process image during each bus cycle. Signal routing uses 1-wire connection technology, so each sensor requires one signal conductor while using a shared return path through the terminal system. The inputs use ground switching to register state changes while limiting the effects of disturbances on the positive supply. The housing measures only 12 mm in width, conserving rail space in densely populated control panels. The terminal can be mounted in any permitted orientation without derating, providing flexibility when arranging compact I/O assemblies around power-feed and communication terminals.