Product Description:

The EL3318 is an eight-channel thermocouple input terminal produced by Beckhoff for the EL EtherCAT Terminals series. It converts low-level sensor voltages into temperature values that can be transmitted across an EtherCAT fieldbus. This allows PLCs to monitor process heat, ovens, or refrigeration lines without separate analog wiring.

Its acquisition chain works with a ±75 mV input span, matching the thermoelectric range of type K sensors as well as B, C, E, J, L, N, R, S, T, U, and plain millivolt sources. It digitizes each channel with a 16-bit converter, which gives 65,536 discrete steps across that span. After linearization, the module forwards temperature data in increments of 0.1 °C, providing fine detail for control loops. A differential destruction limit of ±15 V shields the inputs from miswiring. Eight galvanically separated front spring terminals provide the field side; the count matches the module’s 8 available inputs and follows simple 2-wire connection rules. To avoid false readings, the device detects broken sensor lines, and 500 V isolation separates these field circuits from the EtherCAT bus.

Within the control cabinet, the terminal occupies only 12 × 100 × 68 mm of rail space and carries an IP20 protection class, so it is meant for environments free of direct moisture or dust ingress. Field thermocouple leads may be routed up to 30 m without violating accuracy targets, a distance aided by the module’s ground destruction limit of ±50 V and a ground potential window of ±30 V that suppresses common-mode disturbances. During cyclic communication, the device maps its conversion results into a 16 B In / 8 B Out process image, letting the master exchange status bits and scaling parameters in one frame. Its compact form helps it fit easily into distributed EtherCAT systems.