ELX3204 by Beckhoff

The ELX3204 is an RTD input module produced by Beckhoff within the EL EtherCAT Terminals series. As a DIN-rail device, it installs alongside other EtherCAT I/O slices and feeds temperature data from resistance sensors directly into the fieldbus. The terminal accepts resistance thermometers through a two-wire connection and converts the sensor signals into a digital process image that upstream controllers can use for closed-loop temperature regulation in industrial automation systems.

The module offers 4 differential inputs, allowing four separate RTDs to be monitored without channel-to-channel interference. Each conversion uses 16-bit resolution, providing a fine temperature step size of 0.1 °C/digit across the measurement range. A default conversion interval of 270 ms balances update speed with noise filtering, while the integrated digital filter attenuates unwanted signal components up to its cutoff of 1 kHz. Sensor data are placed in the EtherCAT process image as four 32-bit words, so control programs can read the raw values without additional parsing. Physical dimensions of 15 mm × 100 mm × 70 mm keep the slice width narrow, and the E-bus draws only 70 mA from the backplane.

Backplane electronics are energized by the E-bus at 5 VDC; separate power contacts supply field wiring with 24 VDC, isolating sensor excitation from communication power. The measurement front end is galvanically separated from the logic circuitry by an isolation barrier rated at 1500 V, preventing ground loops between sensors and the controller. An enclosure rating of IP20 provides protection against finger contact and limits the terminal to control-cabinet environments. Cabinet placement also helps protect the exposed connections from moisture, conductive debris, and accidental disturbance during machine operation.