The EL2521-xxxx output terminals change the frequency of a binary signal and output it (electrically isolated from the K-bus). The frequency is preset by a 16 bit value from the automation device. The signal state of the EtherCAT Terminal is indicated by light emitting diodes. The LEDs are clocked with the outputs and each displays an active output.

Special features:

• Pulse train (frequency output)
• Different operating modes
• Frequency modulation
• Pulse direction setting
• Incremental encoder simulation (2x AB)
• Integrated path control
• Synchronized operation through distributed clocks XFC technology possible
• Different output specifications possible
• RS422 version, 5 V DC level

https://www.beckhoff.com/vi-vn/products/i-o/ethercat-terminals/el2xxx-digital-output/el2521.html