EL51xx EtherCAT terminals acquire incremental signals with frequencies up to 5 MHz and feature many parameterization options and integrated functions that enable adaptation to control tasks. Each terminal offers an integrated sensor supply, which is parameterizable to 5, 12 or 24 V. Users can connect encoders with differential RS-422, 5-V TTL or open collector interfaces. Based on internal pull-up resistors, no external wiring is required for open collector analysis. Additional 24-V digital inputs can save, lock and set the counter value. Additional integrated functions, such as rotary axis functionality and standstill monitoring, enable data preprocessing directly in the I/O terminals.