Product Description:

The EL3311-0000 is a thermocouple input terminal manufactured by Beckhoff within the EL EtherCAT Terminals series. It occupies a single I/O slot on the bus and converts analog temperature voltages into scaled digital values that can be read directly by the control CPU. This design eliminates external signal conditioners and supports compact, panel-mounted automation nodes where precise temperature feedback must be transferred over the EtherCAT fieldbus.

The module provides galvanic separation between the sensor side and the bus by means of a 500 V bus-side isolation barrier, protecting adjacent electronics from potential surges. Its electrical measuring window spans ±75 mV, a range that covers common thermocouple outputs while guarding the A/D converter against overvoltage. Conversion takes place with a resolution of 16-bit, enabling sub-degree interpolation when paired with the terminal’s 0.1 °C scaling. Temperature acquisition is handled by 1 input channel that uses a 2-wire connection scheme to keep field wiring simple. Cable runs up to 30 m are permissible between the sensor and the terminal, provided the differential voltage does not exceed ±15 V and the grounded thermocouple potential stays within ±2 V. Open-circuit conditions are detected automatically, and the absence of the EtherCAT distributed-clocks feature means time stamping is managed by the host controller.

The terminal maps its data to the controller through a process image width of 16 bytes in, 8 bytes out, allowing status bits and temperature words to be exchanged during each bus cycle. The housing is rated IP20, so the device is intended for installation inside a control enclosure. It tolerates sensor reference potentials up to ±30 V relative to SGND and withstands inadvertent SGND contact voltages up to ±50 V without damage. Thermocouples of type B, C, E, J, K, L, N, R, S, T, U are supported, and scaled readings advance in increments of 0.1 °C/digit to match the internal fixed-point format.