7800-25 Series Operations Manual
Rev B 11-10-2020
Page 15 of 56
Connecting Alarm Contacts
With the alarm contact feature, a set of terminals on the rear of the unit is provided to
monitor temperature and humidity alarms.
With the alarm contacts, the terminals provided allow for a NO (normally open) output, a
NC (normally closed) and COM (common) connection. In the event of an alarm condition
or power failure, the NO contact will close, and the NC contact will open. Once the alarm
is cleared, the contacts return to their normal conditions. Insert the appropriate wire into
the terminal and tighten down the screw terminal on top of the connector.
Terminal Connection
Unit off
Normal
Alarm
N/O to C
Closed
Open
Closed
N/C to C
Open
Close
Open
Alarm Contact
Connections