EL4008 by Beckhoff

The EL4008 is an analog output module produced by Beckhoff within the EL EtherCAT Terminals series. It fits a single slot on an EtherCAT I/O node and delivers voltage signals to field devices, enabling decentralized actuation in packaging or process equipment. By translating the controller's numeric setpoints into real voltages beside the machinery, the terminal reduces wiring lengths and maintains the deterministic timing required by EtherCAT networks. It uses a single-ended interface suited to field devices that accept referenced voltage commands.

The terminal provides 8 independent analog channels, each mapped in the process image as a 16-bit word that the PLC updates cyclically. Every channel drives a voltage range of 0 to 10 V, which is commonly required by proportional valves, inverters, and instrumentation. Conversion from the internal digital value to the external signal is handled by a 12-bit digital-to-analog converter, providing 4,096 discrete steps and a theoretical output resolution of 2.44 mV. Module electronics draw power from the system's 24 V DC auxiliary rail, so the output stage does not require a separate supply. The polyamide housing meets the IP20 protection class, providing protection against contact with hazardous parts and making the terminal suitable for installation inside a control cabinet.

Signal processing uses multiplexed scanning, which updates each channel rapidly while keeping the circuitry compact. For synchronized operation, the EtherCAT interface supports Distributed Clocks, allowing the outputs to follow network time with submicrosecond accuracy. The housing snaps onto a 35 mm DIN rail, and its variable installation position supports use in tightly arranged panels. All outputs share a common ground, which simplifies wiring but requires appropriate management of return currents. Front terminals provide compact connection points for the field-side signal leads, while status indicators support visual checks during operation.