The DHI-VTNA1040B is designed to cooperation with analog video doorphones and panels of DAHUA.
The device enables connecting and powering up to 4 devices via UTP (Cat. 5e) cables. For large systems the devices can be connected in cascade. Up to 30 devices in the cascade (120 panels in the system). Its using allows to create large surveillance system.
The ability to connect the signal and power together with one UTP cable.