The Zeta addressable zone monitoring units are used to connect conventional detectors to an addressable loop. This may be to cut costs (due to conventional detectors being less expensive compared with addressable ones) or for technical reasons.
The unit has a built in loop short circuit isolator to help maintain operation in the event of a problem on the addressable loop wiring. It has internal indication LEDs for zone alarm (red) and zone fault (yellow) for each of the detector circuits. It also has one for addressable loop fault (isolator active).