EL2124 by Beckhoff

The EL2124 is a digital output terminal produced by Beckhoff within the EL EtherCAT Terminals series. Designed for decentralized I/O architectures, the module supplies low-level control signals from an EtherCAT network to external actuators or indicator circuits in automated machinery. By translating bit commands on the fieldbus into discrete voltage levels on its four channels, the terminal helps reduce cabinet wiring and keeps response times within the microsecond range. It snaps onto the same DIN rail as power modules and analog slices, allowing compact node construction next to drives and sensors.

The terminal provides a nominal high-level output of 5 VDC, so it can drive TTL logic or optoelectronic loads without external level shifters. It has 4 independent channels, each implemented with a CMOS stage that can sink or source up to ±20 mA. Internally, the device maps all channels to the PLC as a compact segment of 4 output bits, minimizing the process-image width on the bus. The typical signal current is 8 mA, which is enough to illuminate diagnostic LEDs or switch high-impedance gates while remaining within the thermal limits of the terminal at 75 °C. Turn-on and turn-off delays remain below 1 µs, maintaining deterministic timing for fast counting or strobed lamp arrays. The output drivers tolerate resistive or lamp loads and are short-circuit protected, helping prevent bus disruptions during wiring faults.

Power and communication are supplied exclusively through the EtherCAT E-Bus backplane, and the terminal draws a typical current of 130 mA from the upstream coupler. The terminal mounts on a 35 mm rail and supports a variable installation position, giving panel designers flexibility in cramped enclosures. An IP20 housing protects the electronics from accidental contact, while ventilation slots help dissipate heat. Operation remains reliable at a relative humidity of up to 95%, so the terminal can be used in control cabinets located in humid production areas when condensation is prevented.