EL2252 by Beckhoff

The EL2252 is a two-channel digital output terminal manufactured by Beckhoff within the EL EtherCAT Terminals series. Designed to dock on a DIN rail beside other EtherCAT terminals, the unit supplies precisely timed output pulses to actuators and sensors in distributed automation cells. By using the protocol's Distributed Clocks feature, the terminal aligns its switching events with sub-microsecond accuracy. This capability supports industrial automation applications that require deterministic timing rather than simple on-and-off control.

The terminal delivers a rated output of 24 VDC per channel and can continuously source up to 0.5 A into resistive, inductive, or lamp loads. Its driver stage uses a push-pull topology, so it can both source and sink current and connect directly to mixed-polarity field devices. The housing has an IP20 protection rating, so the terminal must be installed inside a suitable control cabinet. Deterministic operation is aided by a switching time of < 1 µs, enabling state changes in less than one microsecond. For brief inrush events, the internal limiter supplies 4 A for 150 µs, helping protect the output stage while reducing unnecessary fuse trips. Both digital outputs provide these electrical characteristics, and the Distributed Clocks timing accuracy remains well below one microsecond.

For time-critical motion profiles, each output can receive a hardware timestamp with a resolution of 10 ns. The resulting data occupies 17 bytes plus 4 bits in the EtherCAT process image that is accessible to the controller. Logic power is supplied entirely through the backplane, and typical E-bus current consumption is 130 mA. The separate load supply draws approximately 30 mA in addition to the current required by the connected field devices. The controller can schedule the two outputs independently through the process image, allowing solenoids, indicators, and other compatible loads to switch at times commanded by the EtherCAT master.