Sounder control unit with isolator, 55000-852IMCThe Context Plus XP95 Sounder Control Unit is used to control the operation of a zone of externally powered sounders and to report their status to Context Plus-compatible control equipment.FEATURES
The Sounder Control Unit allows sounders to be operated continuously or pulsed, 1 second on, 1 second off. Sounders may be operated individually or in groups and, whichever address mode has been applied, may be synchronised when in pulsed operation.
An opto-coupled input is provided to monitor the state of the external power supply.  In normal operation the Sounder Control Unit returns a pre-set analogue value of 16, but in the event of an open or short-circuit fault or of a fault in the external power supply, the unit returns a pre-set analogue value of 4.
The Sounder Control Unit is fitted with a bi-directional short-circuit isolator and will be unaffected by loop short-circuits on either loop input or output.
ELECTRICAL CONSIDERATIONS
The Sounder Control Unit is line powered and operates at 17â28V DC. It requires a local power supply of 9â32V DC to power the external load, which may be up to 1.25A. A polarizing diode is required with each alarm device, as sounders are operated by voltage reversal, provided by a double-pole change-over relay. The sounder circuit is protected by a miniature (TR5) fuse rated at 1A.
ADDRESSING
The Sounder Control Unit responds to its own individual address set with a 7- segment DIL switch. It also responds both to a group address, set by means of a 4-segment DIL switch, and to a pulsed-mode synchronisation address which is embedded in the unit.
Addresses 1 to 111 are used exclusively for individual addresses (if â0â is selected on the DIL switch, the Sounder Control Unit will return a pre-set analogue value of 4 to signal a fault); addresses 112 to 126 are used for group addressing, while the synchronisation address, to which all units respond, is â0â. Any Sounder Control Unit on a loop may be freely assigned to a group. The address for any
group must be chosen from the range 112â126. Addresses 112 to 126 may be used as individual addresses but only if the 4-segment DIL switch is set to 127 â group addressing is then disabled. If the 4-segment DIL switch were set to any number other than 127, a pre-set analogue value of 4 would be transmitted to indicate a fault.
