Carel UU01F1, User Manual, Page: 69 / 72

16.5 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
humiSonic 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 main unit. 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;
Main board
Backup unit
Auxiliary board
Main unit
M 15
J17
Main board
Main unit
Auxiliary board
Backup unit
M 15
J17
Alarm
relay
Alarm
relay
• 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 configured suitably (see chap. “Configuration
parameters”, table parameter b0) both on 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 request
signal/measurement o dew point temperature; 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.