Secondary Unit Acting As Backup For The Main Unit - Carel HumiSonic Manual Del Usuario

15.6 Secondary unit acting as backup for the
main unit
For "mission critical" applications in which service continuity must be
guaranteed, a secondary humiSonic can be set as backup for the main
humiSonic unit. The backup unit will be activated only if the main unit
shuts down (due to an alarm). Observe the following points to correctly
enable the backup function:
• auxiliary card also fitted on the both main unit and backup;
• electrical wiring from alarm relay output on the main unit to auxiliary
input J17 on the secondary, and vice-versa from alarm relay output on
the secondary to auxiliary input J17 on the main unit;
Auxiliary board
Main unit
J17
Alarm
relay
Auxiliary board
Backup unit
J17
Alarm
relay
Fig. 15.b
• dipswitch 1 on the main unit and the backup unit in the OFF position;
• dipswitch 2 or 3 on a backup unit in the ON position;
• request signal also sent to the backup unit;
• parameter b0 suitably configured (see chap. "Configuration parameters"
Tab. 9.c) on both the main unit and backup, so as to:
1. enable the backup function on both;
2. activate the alarm relay for active alarms on both.
NOTICE:
the connector body needed for input J17 is a Molex two-pin
male Minifit housing Molex 5556-T female terminals.
When the main unit is not powered off and has no alarms (alarm relay
contact closed), the display on the backup unit will show the disabled
message "b - -" on the main screen, alternating with the humidity or dew
point request signal/measurement; vice-versa, when the alarm relay
contact on the main unit is open, the backup unit will be enabled for
production.
When the backup unit is powered down or has an alarm, "-bu" (see alarm
table) will be shown on the display on the main unit, meaning the backup
unit is not available.
Auxiliary board
Backup unit
J17
Auxiliary board
Main unit
J17
35 Direct version for room applic. +0300062EE - rel. 1.4 - 24.09.2020
ENG