3672 Alarm Output Module

3672 Alarm Output Module
Alarm Output
Item # 3672
The Alarm Output Module (AOM) is a dry contact,
control relay that operates as either a normally-open or
normally-closed single pole switch. The output is rated at 1 amp AC or DC. It should be used with low
voltage control signals due to its exposed terminal
The relay is triggered when a sensor reading
“exceeds” the user-defined set point. The user can
select whether the relay is activated when the set point
is truly exceeded or when sensor readings drop below
the set point. This is accomplished by selecting either
“Goes Above” or “Goes Below” in the SpecWare
Launch Options screen (See image below). The relay can trigger on any of the pre-connected sensors
(wind speed, rainfall, air temperature or relative humidity) as well as any sensor on Ports A - D (i.e. leaf
wetness, soil moisture, etc.). The relay is reset as soon as the set point is no longer “exceeded”. Set
points are entered as a whole number or decimal depending on how the selected sensor reports its reading. If the station is functioning in metric mode, all set points should be in metric as well.
Specware uses lookup tables to convert the sensor’s electrical response into physical data points so only
a finite number of values are actually available. If the Alarm Set Point does not identically match one of
these discrete values, the software will replace it with the closest corresponding value in the lookup table. Therefore, when the Launch Options screen is displayed, the Alarm Set Point may differ slightly
from what was originally entered.
Rainfall is a special case. The rainfall set point is the amount of rain that falls during the logging interval. The relay is not activated/deactivated until the end of the interval. Example: If the set point is
0.15”, the relay will activate at the end of the first interval that records 0.15” of rain. It will then deactivate when succeeding interval has recorded less than 0.15”.
A splitter is included with the Alarm Module for applications where the weather station’s Auxiliary Port
is needed for some other function (i.e. for connecting a wireless transceiver).
3600 Thayer Ct.
Aurora, IL 60504
(800) 248-8873 or (815) 436-4440
Fax (815) 436-4460
E-Mail: info@specmeters.com
Notes on the operation of the alarm output module
The AOM is a latching relay. That means it remains in the last state it was set in. It does not revert to a
default state when power is removed. When the module is connected to the station and the alarm condition does not exist, the relay will be on the normally closed (NC) terminal. When the alarm condition
exists, it will switch to the normally open (NO) position.
Example: Alarm output module wired to an auto-dialer that triggers a phone call when temperature
moves below 34F. In Specware, set Alarm thresholds to trigger the device when Temperature is below
34. The other field should be set to an unattainably high value (say, temperature is greater than 999F).
This assures that the station will only trigger the alarm at one threshold. The auto-dialer should be
wired to the COM and NO terminals. Under warm conditions, there will be an open circuit. When the
temperature drops below 34, the COM-NO circuit will close and the auto-dialer will be triggered.
Full Stations
If the AOM is “off” (continuity on COM-NC), it will automatically turn “on” (continuity on COM-NO)
if it is plugged into a station where the alarm condition exists. It could be up to 20 seconds before the
AOM switches because it will not switch until the sensor values are refreshed.
The opposite is not true. If the AOM is in the “on” position (continuity on COM-NO), and connected to
a station where the alarm condition does not exist, it will not automatically switch “off”. It must be connected to a station as it passes from the alarm-on condition to alarm-off.
Mini Stations
For mini stations, the AOM will not change states after being plugged into the station. The AOM must
pass into the alarm condition to change it from off to on. It must pass out of the alarm condition to turn
it from on to off.
If the relay is in the activated state when the station is contacted for a download or launch, the relay will
remain active until:
1.) Station is successfully relaunched with “No Alarm” selected in the Launch Options screen.
2.) Station is successfully relaunched and conditions are such that the set point is no longer
“exceeded. At that point, the relay automatically resets itself.
Note: Weather stations must have firmware version 7.0 or greater to function with the Alarm Module.
However, only condition 2 will work on versions 7.0 and 8.0. The firmware version is displayed in the
Launch Options screen.
The AOM will not work properly for mini stations with firmware 3.7 to 4.1.
R - 04/17
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