The fire alarm interface comprises two parts, a conventional system interface and an analogue sys-
temn interface. It should be noted that BS5839-8 requires all controlling inputs to be latched
and all links to be monitored. Depending on the facilities available at the controlling equip-
ment, this is not always possible. In such cases it is acceptable to have unmonitored links pro-
vided they are very close and at least IP30 protected. One way to do this is to mount the control
equipment next to AVAC so there is no gap between them.
The conventional interface
The conventional interface has four polarized inputs, Evacuate (M1), Alert (M2), Test (M3) and Reset
(RES) plus a fault relay output. All four inputs are optically isolated and designed to be active when
supplied with +24 V. For compliance with BS5839-8, all four conventional inputs are set to latch by
default (i.e. Link 3 of the PLK4 option links is supplied fitted). When a steady voltage of +24 V is
applied to an input, the relevant message plays until a higher priority message is asserted (note that
pulsing inputs are not compatible with AVAC). When the trigger voltage is removed, the selected
message will continue to play. Only when the AVAC’s Reset input is asserted will the system return to
normal. When the Reset stimulus is released no message will play unless other inputs are asserted.
Note, the fire panel’s Reset input should be set to activate when the fire detection system is
SILENCED or RESET, not just when reset.
Note that Apollo protocol analogue
systems can be connected directly to
AVAC’s analogue interface, as
described on page 18.
When interfacing a non-Apollo ana-
logue addressable fire alarm system to
the conventional interface, the M1,
M2, M3 and RES inputs are usually
triggered via one or more input/out-
put units, as shown. The I/O units
should be programmed via the fire
panel’s own programming software
to operate as appropriate. To meet
BS 5839-8, the I/O units should be
mounted adjacent to the Master
AVAC(s) such that they can be consid-
ered to be one cabinet.
When interfacing a conventional fire alarm panel to
the conventional interface, the M1 (Evacuate) input is
normally triggered via a monitored sounder circuit or
relay. The M2 (Alert) input is normally not used in
this scenario as pulsing inputs are not compatible
with AVAC. As most conventional
panels do not have a monitored
silence input that is capable of driving
AVAC’s reset input, removing Function
Link 3 on AVAC’s PLK4 option links
will set all message inputs to non-
latching.
For this arrrangement to meet the
spirit of BS5839-8, the control panel
must be mounted adjacent to the
Master AVAC(s) such that they can
be considered to be one cabinet.
AVAC VOICE ALARM SYSTEM
AVAC Installation and Maintenance Manual • Approved Document No. DAU0000402 Rev 6 • Page 17
FIRE ALARM INTERFACE CONNECTION
INPUT
MONITOR
I/O UNIT
RES
M3 (TEST)
M2 (ALERT)
M1 (EVAC)
INPUT
MONITOR
AD
DR
ES
SA
BL
E
LO
O
P
–
+
+
–
+
–
–
+
I/O UNIT
NO
C
I/O UNIT
EOLD
NC
FAULT
RELAY
0V
+24V
AVAC
MAIN PCB
TEST SWITCH
LOOP
ISOLATOR
LOOP
ISOLATOR
Program the two I/O units via the
fire panel’s programming
software to operate as
appropriate. Note that both I/O
units must be at rest to reset
1
2
3
4
1
2
3
4
PLK4
1
2
3
4
1
2
3
4
PLK4
M
es
sa
ge
Fu
nc
tio
n
M
es
sa
ge
Fu
nc
tio
n
1
2
3
4
1
2
3
4
PLK4
M
es
sa
ge
Fu
nc
tio
n
1
2
3
4
1
2
3
4
PLK4
M
es
sa
ge
Fu
nc
tio
n
1
2
3
4
1
2
3
4
PLK4
M
es
sa
ge
Fu
nc
tio
n
Remove link 3
to make message
inputs non-latching
Interfacing a conventional fire system to AVAC’s conventional interface
RES
M3 (TEST)
M2 (ALERT)
M1 (EVAC)
NO
C
SOUNDER
CIRCUIT
EOLD
NC
–
+
+
–
+
–
–
+
+24V SOUNDER
CIRCUIT
0V
FAULT
RELAY
0V
+24V
AVAC MAIN PCB
CONVENTIONAL
FIRE PANEL
TEST SWITCH
MONITORED
Interfacing a non-Apollo analogue addressable fire system to AVAC’s conventional interface
