IE3112 by Beckhoff

The IE3112 is an analog input extension box built by Beckhoff for the IE Extension Box Units series. Intended for decentralized mounting, it converts field current signals into a digital format for transmission over EtherCAT to the control cabinet. Locating signal conditioning near sensors shortens wiring and preserves measurement fidelity in distributed automation systems.

The module provides 4 independent current channels, each with a nominal range of 0 to 20 mA. A front-end input resistance of 80 ? supports shunt conversion, while the sigma-delta converter delivers a resolution of 15 bits plus sign. Typical sampling of all channels is completed within 140 ms, making the unit suitable for slow- to medium-speed control loops. Up to 10 selectable digital filters allow users to adjust noise suppression without external hardware. Across the full scale, the maximum relative error does not exceed ±0.3% FS. Internal multiplexing means the channels share an ADC path, so the channels are not isolated from one another. The process image transfers four 16-bit words, and an auxiliary block provides optional I/O mapped as four 8-bit registers plus four 16-bit registers.

Electrical safety on the IE3112 is supported by channel-to-housing isolation rated at 500 V, while the permitted common-mode level on any input must remain below 35 V. The control circuitry is galvanically isolated from the EtherCAT fieldbus, so accidental ground shifts do not propagate into the network. Wiring is simplified through M12 screw-in connectors for signal inputs. Supply power is routed through one male and one female four-pin M8 connector, allowing daisy-chain distribution along a machine. A sensor supply rail is available and can provide up to 30 VDC to two-wire transmitters. Additional diagnostic bits in the process image report undervoltage or wiring errors, complementing the physical isolation features and giving the controller clear fault visibility.