The EL9520 potential feed terminal decouples the input and output signal with an integrated filter and enables the supply of AS interface networks from standard power supply units or from another AS interface network. The EL9520 can be placed directly adjacent to the EL6201 AS interface master terminal. The parallel operation of this combination in an EtherCAT terminal block is possible several times and saves several AS interface power supply units.
https://www.beckhoff.com/vi-vn/products/i-o/ethercat-terminals/el9xxx-system/el9520.html