EL1889 by Beckhoff

The EL1889 is a digital input terminal manufactured by Beckhoff within the EL EtherCAT Terminals series. It converts field signals into the EtherCAT process data stream, allowing a controller to capture machine states over a single I/O bus. The terminal installs alongside other EL modules on a standard DIN rail, which supports compact and orderly control cabinet layouts. Its ground-switching input channels receive power through the contacts connected to the adjacent supply terminal.

Each input channel uses 1-wire connection technology, so one conductor carries the signal while the channels share a common ground. The EtherCAT backplane supplies logic power, and the terminal draws a typical E-bus current of 110 mA, which must be considered when determining the total load of a node containing several modules. Each connected field sensor places a load of only 3 mA on the input stage, reducing the wiring burden for proximity switches and contact blocks. A hardware filter with a response time of 3 ms suppresses contact bounce and brief electrical disturbances before each state is transferred to the controller. The inputs are referenced to the power contact and accept a nominal input voltage of 24 VDC. The terminal exports 16 input bits to the process image, allowing the PLC to read the on-off state of every channel during each bus cycle.

The power-through design places a typical load of only 35 mA on the power contacts, while higher sensor currents pass through the terminal's power distribution path. The housing has an IP20 protection rating, making it suitable for installation inside a closed control cabinet. This rating protects against accidental finger contact and solid objects larger than 12.5 mm, but it does not provide protection from water. The terminal block has an overall width of 12 mm, preserving rail space for neighboring I/O and power modules. Connected-through power contacts distribute field power across the terminal assembly without requiring separate supply wiring for every module.