MCC
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9
2.2
OPERATION ROLES
MCC may be operating as a master, as a slave or under an
“undefined” state:
The
master
aims at actually controlling the room climate.
The
slave
remains waiting for a failure in the master, to take over the climate
control.
A device i
s operating as “
undefined
” when it has not been determined yet
whether it must operate as a master or as a slave.
The device role will be notified via communication object (this process is detailed in
following sections) and by two LEDs specifically included for this purpose: the LED
corresponding to the current role lights up (
master LED indicator or slave LED
indicator
); if there is no role assigned yet (see section 2.3), both LEDs remain off.
The integrated thermostats do not start operating until the device has a role assigned.
When the device adopts a role, it will start performing the thermostat actions as if a
restart had just taken place. Moreover, on the first execution, the
thermostat actions
that may apply after an ETS download will also take place
.
The following sections describe the master and slave operating modes.
2.2.1
MASTER
The master handles the
climate control
by sending the control orders and states
(communication objects) when required.
While the device is operating as a master, the master LED indicator is on.
2.2.1.1
COMMUNICATION OBJECT NOTIFICATIONS
Periodically (time set by parameter), the master device sends
a ‘1’ through the master
notification communication object, and afterwards its internal checksum value.
If
a master device receives any value through the master notification object
,
automatically switches to slave mode (and sends the corresponding slave notification).
