Product Description:

The EL6021-0021 terminal is a single-channel serial interface module produced by Beckhoff and placed in the EL EtherCAT Terminals series. Designed for mounting on a DIN rail alongside other I/O nodes, the device introduces an RS422/RS485 line into an EtherCAT network, allowing controllers to exchange serial data with sensors, drives, and operator panels. In an automation cell, it functions as a protocol bridge that converts fieldbus process data into differential serial telegrams without requiring a separate gateway.

This module presents one RS422/RS485 port that can operate in full-duplex or half-duplex mode with selectable TxD and RxD directions. Communication speeds scale from the default 9600 baud configuration up to 115200 baud, supporting 8-N-1 framing for compatibility with common equipment. To maintain electrical integrity on long wiring runs, the interface is galvanically isolated from the internal logic by a 500 V test voltage and expects a line impedance of 120 Ω. The EtherCAT backplane supplies the logic through an internal demand of 170 mA on the E-bus, eliminating the need for external 24 V wiring. Cable segments as long as 1000 m are permitted when shielded twisted pairs are used, allowing installation of remote operator stations or barcode readers. Enlarged bias resistors keep idle lines at a defined potential, and the differential signal type helps reduce noise pickup.

Data exchanged with the controller is organized in a 22×8-bit I/O map that is accompanied by 16-bit control and status words, so the controller can monitor link state while processing payload bytes. Received characters are buffered in 864 bytes of memory, and outgoing telegrams are staged in a 128 bytes transmit FIFO to reduce the chance of bus congestion during burst traffic. The terminal carries an IP20 enclosure rating, measures 12 mm × 100 mm × 68 mm, and is powered exclusively from the E-bus rail. Differential signaling supports stable data transfer across extended runs within the network cycle.