EL1808 by Beckhoff

In industrial EtherCAT networks, the Beckhoff EL1808 functions as a digital input terminal within the EL EtherCAT Terminals series. The device translates discrete sensor states into cyclic bus data so programmable logic controllers can supervise machine interlocks and operator commands. Mounted as one slice in a DIN rail stack, it supplies compact, field-level I/O that scales with the channel count required by automated equipment. Its modular format allows the terminal to be installed alongside other EtherCAT I/O slices serving the same control system.

The nominal input voltage is 24 VDC, aligning with standard control power supplies used for industrial sensors. The optically isolated channels occupy 8 bits in the process image, so the controller reads their states as a single byte during each bus cycle. Each channel draws a typical 3 mA, minimizing the electrical load placed on connected proximity switches and other sensing devices. A hardware input filter of 3 ms suppresses contact bounce before the logic stage updates the corresponding input state. Compliance with the EN 61131-2 Type 1/3 signal standard ensures that the permitted voltage thresholds and current characteristics match common sourcing devices. Optical isolation separates the field signals from the internal bus electronics and helps prevent disturbances on sensor wiring from affecting data communication.

The terminal offers 16 screwless spring contacts arranged in a 2-wire format, providing separate signal and reference connections for each channel while keeping the overall width to 12 mm. Internal electronics consume 100 mA from the E-bus, and the reference ground is tied to the 0 V power contact to keep sensor returns local to the terminal. Front-panel LEDs illuminate green to indicate active input states, allowing channel activity to be viewed directly at the cabinet. The enclosure has an IP20 protection class and is intended for installation inside a suitable control cabinet. The unit clips onto a 35 mm DIN rail without additional mounting hardware. Its narrow housing supports closely spaced input terminals while preserving access to the spring contacts and status indicators.