Beckhoff EL3356-0010 EtherCAT Terminal for Strain Gauge Sensors

The Beckhoff EL3356-0010 is an EtherCAT digital input terminal designed for direct connection of strain gauge full‑bridge sensors. It provides a 24‑bit delta‑sigma analog‑to‑digital converter (ADC) with a sampling rate of up to 10 kHz, making it suitable for high‑precision weighing, force measurement, and tension control applications. The terminal integrates excitation voltage (10 V DC) and can be used with 4‑wire or 6‑wire strain gauge bridges. The measured values are transmitted via the EtherCAT fieldbus with minimal latency, enabling high‑speed closed‑loop control.

Technical Specifications

Functional Description

The EL3356-0010 is designed specifically for strain gauge sensors, such as load cells and force transducers. The built‑in excitation voltage powers the bridge, and the differential analog input amplifies and digitizes the signal. The terminal performs internal ratiometric measurement, compensating for excitation voltage variations, which eliminates the need for an external reference voltage. The 24‑bit ADC provides a high dynamic range, allowing micro‑strain measurements. The integrated filter can be configured for 50 Hz or 60 Hz noise suppression, ideal for weighing applications. The EtherCAT distributed clock synchronizes the measurement with other I/O devices with a jitter of less than 1 µs.

Configuration and Calibration

Configuration is performed using TwinCAT System Manager. The user can set the sampling rate, filter frequency, and data format (integer or 64‑bit floating point). Calibration is supported via two methods: using known physical weights (gain/offset) or using a mathematical model based on sensor specification. The terminal stores calibration coefficients in non‑volatile memory. The data output is provided as a 64‑bit integer (scaled to 0.1 nV/V) or as a 64‑bit real‑world value in engineering units (e.g., kg, N).

Diagnostic Features

LED indicators on the module show EtherCAT status and sensor connection health. A red ERROR LED indicates an open circuit or short‑circuit of the bridge. The module also monitors the excitation voltage and reports under/overvoltage conditions. Diagnostic messages are transmitted to the EtherCAT master and can be displayed in TwinCAT.

Applications

The EL3356-0010 is used in high‑precision industrial scales, dynamic checkweighers, force measurement in press‑fit systems, tension control in web processing, and material testing machines. Its high sampling rate (10 kHz) makes it suitable for capturing transient forces in high‑speed manufacturing lines.

Installation and Wiring

The terminal is mounted on a Beckhoff EtherCAT coupler (EK1100) or on any EtherCAT bus terminal block. Connect the strain gauge bridge using a 6‑wire configuration (sense lines) for best accuracy. Use shielded twisted‑pair cable, with the shield connected to ground at the module end. The terminal has a 16‑pin spring clamp terminal for field wiring. The power supply for the excitation is derived from the 24 V DC bus, which must be capable of supplying at least 0.5 A for the terminal and sensor.

Conclusion

The Beckhoff EL3356-0010 provides a compact, high‑accuracy interface for strain gauge sensors, delivering real‑time measurement data over EtherCAT for precision control and monitoring applications.