Product Description:

The EL3172 is a two-channel differential analog input terminal produced by Beckhoff for the EL EtherCAT Terminals series. Installed on a DIN rail, it mates with adjacent I/O blocks through the internal E-bus to pass power and data to the network. The terminal digitizes field signals so an EtherCAT master can acquire synchronized process values and issue time-critical commands inside automated machinery.

The module offers 2 differential input channels that are sampled by a successive-approximation register, identified by the SAR converter type. Each conversion delivers 16-bit resolution, allowing 65,536 discrete steps per measurement. A built-in analog front end limits bandwidth with a 5 kHz input filter, suppressing high-frequency noise before conversion. Because the two channels share a simultaneous sampling scheme, both values are captured at the same instant, which is important for phase-sensitive control. The EtherCAT interface can update the process image every 175 µs, matching fast control loops while still leaving bus time for additional terminals. The ground reference is differential, so the pair of inputs measures the voltage difference between the positive and negative leads instead of using the supply ground, reducing common-mode errors in electrically noisy installations.

E-bus logic draws a typical 140 mA, a figure that helps with sizing the power budget for large terminal strings. Functional isolation is verified by an insulation test of 707 V for 7 s, separating field wiring from the backplane to protect the controller. At the screw contacts, each channel can source or sink up to 40 mA without damage, supporting most passive sensors. The housing is rated IP20, so it must be placed inside a cabinet that protects it from dust and dripping liquids. Configuration data are stored locally, and the module supports nonvolatile storage, allowing it to retain settings when the system is powered down.