The EL1722 digital input terminal acquires the binary control signals from the process level and transmits them, in an electrically isolated form, to the higher-level automation unit. The direct connection of 120 V/230 V AC signals is possible. The EtherCAT Terminal has two channels that indicate their signal state via light emitting diodes. The EL1722 has no power contacts. This makes it possible to create individual potential groups. The voltage between input 1 and input 2 must not exceed 230 V AC.

Special features:

• direct connection of 120 V/230 V signals
• for AC voltage
• creation of individual potential groups is possible (no power contacts)

https://www.beckhoff.com/vi-vn/products/i-o/ethercat-terminals/el1xxx-digital-input/el1722.html