TTL NETWORK MANAGEMENT
No Master-Slave communication: the
slave fan coil cyclically await the zone
settings from the master fan coil. If for
some reason a slave fails to communi-
cate with the master, it switches OFF
(i.e. shutdown of all loads) after 10"
from the last command successfully
received.
No Master-User Interface communica-
tion: if at some point the master no
longer communicates with the user
interface, it switches OFF after 10" from
the last command received from it. The
master will also send the OFF com-
mand to all the slaves. The user inter-
face also gives the visual alarm AL 1
TTL NETWORK CONSTRAINTS
The constraint concerns the management
of the adjustment dead band; this should
be set on the master fan coil being that it
is ignored on the slaves because both the
setpoint and the operating season of these
depend on the master.
T T L
N E T W O R K
E M E R G E N C Y
FUNCTION
Master without Ambient Probe
The operating principle of the master
thermostat in the event that it functions
without ambient probe (or fault of its
T T L N E T WO R K A N T I - F R E E Z E
PROTECTION
Master: As described in the ANTI-
FREEZE PROTECTION paragraph, the
thermostat foresees as standard the
control of the ambient temperature to
prevent this fall to freezing values. If
the master has to operate in this condi-
tion, it will impose all slaves to oper-
ate in AUTO mode with setpoint at
12° C, even though these are operating
according to normal conditions.
local probe) follows what described in
the next paragraph.
Slave without Ambient Probe
The Slave thermostat cards enter into
emergency mode not only if the local
probe is faulty but also if the master
one is faulty too. According to what
previously mentioned, if the slave
probe is faulty and the master probe is
working properly, the slaves continue
to operate using that one of the master.
If the slaves begin to work in emer-
gency mode, they will be operated at
the speed selected in the user interface
and the valve Y1 is opened (this applies
for both 2-pipe and 4-pipe system).
Furthermore, the slaves in emergency
mode do not follow the logic of the
ON-OFF cycles based on the position
of the temperature selector but are
always in the ON phase, therefore with
ventilation always running.
Slave: Whereas if it is one of the slaves
operating according to the anti-freeze
protection (despite the master is oper-
ating in normal mode), it will oper-
ate in AUTO mode with setpoint at
12° C. This is the only case in which
the slave operates according to set-
tings different to those dictated by the
master.
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