ELM3004-0000 by Beckhoff

The ELM3004-0000 is an analog input module manufactured by Beckhoff for the ELM EtherCAT Terminals series. It operates as a differential measurement terminal that digitizes process voltages and currents. The resulting data allow a controller on the EtherCAT network to perform high-speed acquisition and closed-loop regulation in industrial automation systems.

The hardware integrates 4 differential channels through a shared converter architecture that supports simultaneous conversion, preventing phase errors between signals. Each channel is digitized with a 24-bit resolution, providing low-noise capture for precision sensing tasks. The internal ADC core runs at 8 Msps, while oversampling and digital filtering reduce the raw rate to an application-accessible throughput of 10 ksps per channel. A selectable analog input filter limits spectral content to 30 kHz, and an additional ADC filter operating at 2.6 kHz reduces residual quantization noise. Eleven measuring ranges can be selected through software, and the module reaches a steady filter response after a 300 µs ramp-up period. The channels are not galvanically isolated from one another, but the terminal provides 707 V DC of system isolation between signal ground and the E-bus to protect upstream control equipment.

The module typically draws 470 mA from the communication backplane. Power dissipation is limited to 3 W, so heat generated during signal conversion can be conducted through the housing without an external heat sink. The enclosure has an IP20 rating, providing protection against accidental finger contact but no protection against water. Field wiring uses a two-wire connection scheme that simplifies the routing of differential signal pairs. The compact design omits channel-to-channel isolation, reducing the space required within the terminal housing while retaining isolation from the EtherCAT supply.