EL5002 by Beckhoff

The EL5002 is an encoder interface terminal produced by Beckhoff for the EL EtherCAT Terminals series. Designed for machine controllers that use fieldbus I/O, the unit connects serial encoders to the network and transfers position data to the PLC in real time. Its 12 mm-wide housing conserves cabinet space while supporting synchronized position feedback for motion axes, conveyors, and metrology stations in industrial automation systems.

The terminal provides 2 independent input channels, allowing one compact unit to receive feedback from a pair of position sensors. Each channel uses the SSI protocol, through which a 25-bit or similar serial data frame is clocked out of the connected encoder during every sampling cycle. Physical signaling complies with the differential RS-422 standard, which improves noise immunity when signals travel through long shielded cables. Clock pulses can operate at up to 1 MHz, enabling frequent position updates for fast-moving axes. After conversion, the position words are published on the network with deterministic timing, even when many terminals share the same bus segment.

The connected encoder must provide an absolute data stream, meaning each frame contains the complete position value and eliminates the need for homing after a power loss. The terminal electronics operate from 24 VDC, allowing connection to common industrial control power supplies. Support for distributed clocks allows the terminal to synchronize its internal timer with the fieldbus master, minimizing jitter between data acquisition and drive commands. This timing capability helps coordinate measurements from separate axes while maintaining a consistent relationship between sampled positions and control cycles. The terminal can be installed alongside compatible analog, digital, or safety I/O modules without additional gateway hardware.