900 Series V5.1: Installation Guide, February 2000 25
Electrical considerations:
The Series 950 DIN-rail sounder control unit is loop powered and operates at 14-
28 VDC. It requires a local power supply of 9-50 VDC to power the external load,
which can be up to 1 A.
Use a polarising diode with each alarm device (if not pre-fitted to the sounders), as
sounders are operated by voltage reversal provided by a double-pole changeover
relay. A miniature (TR5) fuse rated at 1 A protects the sounder circuit.
Addressing:
The Series 950 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 that is
embedded in the unit.
Addresses 112 to 126 can be used as individual addresses but only if the 4-
segment DIL switch is set to 127 – group addressing is then disabled. If the 4-
segment DIL switch is set to any number other than 127, a fault is indicated.
In alarm conditions it might be desirable to switch more than one Sounder Control
Unit simultaneously. To do this, link the units together to form a group and give
them a group address that is common to all the units in the group.
Individual address setting: Set the individual address of the sounder control unit
using seven segments of the eight-segment DIL switch. The eighth segment is set
to 1 if it is required to disable the fault LED. Set each of the other seven segments
to 0 or 1 using a small screwdriver or similar tool (refer to Table 2: DIL address
settings).
Group address setting: In group mode, the Sounder Control Unit responds to an
additional address, called the group address, which simultaneously activates
groups of Sounder Control Units. Individual units continue to respond to their own
addresses and report their own status from their address in the normal way. Set a
group address on a four-segment DIL switch, which is factory set to 0000. A group
address can be any spare address within - and only within - the range 112 to 126
inclusive. Moving one or more of the segments on the switch to 1 in accordance
with the following table, sets the required group address:
Table 3: Group configuration for DIN mounted sounder controller
ADDR 1234 ADDR 1234 ADDR 1234
112 1111 117 0101 122 1010
113 0111 118 1001 123 0010
114 1011 119 0001 124 1100
115 0011 120 1110 125 0100
116 1101 121 0110 126 1000
Fault monitoring:
As well as monitoring open and short-circuit faults on the sounder wiring, the
sounder control unit can also monitor the presence and polarity of the external
power supply to the sounders. This is achieved by using a circuit that includes an
input to monitor a volt-free, normally open contact. A wire link must be fitted if the
fault contact is not used.
If the fault LED is not required, or the extra loop current to illuminate it, is
unavailable it can be disabled by using the eighth segment of the DIL switch.
The red LED is powered from the external supply and is always enabled.
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