Apollo XP95 Loop-Powered Visual Indicator is a local-area visual indicator designed for indoor use. The visual indicator has been developed as a supplement to sounders for use in situations where there is a risk that sounders will not be heard. The base is loop powered so needs no external power supply. It operates at 17 to 28VDC and is polarity-sensitive. The base is moulded in polycarbonate and has stainless steel contacts that accept solid or stranded cables of up to 2.5mm². The base responds to its own individual address set with a DIL switch. It also responds to a group address, set by means of a 4-segment DIL switch and to a synchronisation address which is embedded in the unit. Addresses 1 to 111 are used exclusively for individual addresses, addresses 112 to 126 are used for group addressing, while the synchronisation address, to which all units respond is 0. Any beacon base on a loop may be freely assigned to a group. The address for any group must be chosen from the range 112 to 126. Addresses 112 to 126 may be used as individual addresses but only if the 4-segment DIL switch is not used that is, group addressing is disabled. If the 4-segment DIL switch were set to any number other than the default 127, a pre-set analogue value of 4 would be transmitted to indicate a fault. The base is normally polled by its individual address and it responds as described below. It is recommended that the synchronisation address 0 be sent by the control panel at regular intervals to align the internal clock of all sounders. The result is that the beacons are synchronised with each other when activated. The base will operate only with control equipment using the Apollo XP95 or Discovery protocol. The features of the base are available only when it is connected to a control panel with the appropriate software.