Carel humiSonic UU02, User Manual, Page: 65 / 68

13.6 Slave unit acting as backup for the
Master unit
For “mission critical” applications in which service continuity must be
guaranteed, a humiSonic slave can be set as backup for the humiSonic
master (main unit). The backup unit will be activated only if the main unit
shuts down (due to an alarm), operating based on the request signal sent
to the Master. From a wiring point of view, this function uses the network
connection as described in the previous paragraphs, in addition to the
following:
• auxiliary card also fitted on the backup slave unit;
• electrical wiring from alarm relay output on the master to auxiliary
input J17 on the slave, and vice-versa from alarm relay output on the
slave to auxiliary input J17 on the master;
Auxiliary board
Slave unit
Auxiliary board
Master unit
J17 J17
Auxiliary board
Master unit
Auxiliary board
Slave unit
Alarm
relay
J17 J17
Alarm
relay
Fig. 13.a
• parameter b0 configured suitably (see chap. “Configuration parameters”
Tab. 7.c) both on the master (main) and slave (backup), so as to:
1. enable the backup function on both;
2. activate the alarm relay for active alarms on both;
3. set NO logic for the alarm relay on the master and NC logic for the
alarm relay on the slave.
Note: the connector body needed for input J17 is a Molex two-pin
male Minifit housing Molex 5556-T female terminals.