Product Description:

The EL7051 is a stepper motor interface terminal from Beckhoff that belongs to the EL EtherCAT Terminals series. Installed on a DIN-rail as part of an EtherCAT I/O rack, it drives two-phase stepper motors directly from the backplane power and exchanges position data with the controller through distributed clock synchronization. In positioning or indexing stations, the terminal converts command words into phase-controlled current waveforms so that a compact motion axis can be built without a stand-alone drive.

The output stage is designed for a rated supply of 80 V DC, giving the terminal enough headroom for high-speed moves on long motor cables. It sources up to 8 A peak current, so mid-frame hybrid steppers can be accelerated without external boosters. Motion smoothness is improved by 64-fold microstepping; this divides one full step into sixty-four smaller electrical increments and reduces resonance in light-load mechanisms. Four differential encoder channels are accepted; the presence of 4 encoder inputs lets the PLC verify actual shaft position and detect loss of synchronism. These inputs expect an incremental signal, allowing direct hookup of common quadrature encoders for closed-loop stepper control.

Communication takes place on the EtherCAT fieldbus, so position, velocity, and diagnostic data appear in the same process image as other machine variables with microsecond-level determinism. For move counting that must continue even if the bus is interrupted, an integrated internal counter tallies steps locally. End-of-travel verification is handled through 2 × 24 V DC limit inputs; these digital channels stop the PWM stage as soon as the sensors break the circuit. The final current waveform is generated by a PWM amplifier, translating position commands into pulse-width-modulated phase currents that keep motor heating under control while sustaining torque.