EL3051 by Beckhoff

The EL3051 is an analog input terminal from Beckhoff in the EL EtherCAT Terminals series. It converts a process-side 4 to 20 mA current loop into digital words that an EtherCAT controller can read, making it suitable for pressure, level, or position transmitters in distributed I/O stations. Its single channel is referenced to a common ground. The module fits into the series' 12 mm housing and snaps onto a DIN rail alongside other signal types without requiring additional wiring adapters.

This terminal accepts a loop range of 4 to 20 mA and routes the signal through a 30 V dielectric barrier so that higher field voltages do not reach the bus side. Internally, the signal passes through a 1 kHz filter that suppresses high-frequency noise before conversion at a native resolution of 12 bits. The terminal pads the resulting value to 16 bits for uniform data alignment within the EtherCAT frame. Typical measurement deviation remains below ±0.3% of full scale, supporting closed-loop applications that require consistent accuracy. The module provides one single-ended analog input and does not support Distributed Clocks, so upstream devices must handle time stamping.

Conversion uses simultaneous sampling, and the process image allocates 2 bytes for status and 2 bytes for the value during each bus cycle. Reliable operation is maintained from -25 to +60 °C. Operation outside this temperature range requires appropriate derating, while the powered-down electronics can be stored from -40 to +85 °C. The IP20 housing limits the ingress of solid objects and is intended for installation in a protected control cabinet. Ground referencing simplifies connections in loop-powered circuits, while the lack of distributed clocking provides predictable module latency for analog trend acquisition. The terminal's narrow housing also supports dense I/O arrangements where several signal channels must share limited DIN-rail space.