DAVIS WeatherLink for Alarm Output Add. - Manual (Page 15)

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the previous settings. Thus, you may notice the program takes longer times
than others to set values.
Notes on parameters:
• Barometer Trend parameters: Use the True check type for this parameter.
Each of the four barometer trends (rising rapidly, rising slowly, steady,
falling slowly, and falling rapidly) when used will alarm separately. If
you wish to trigger an alarm if the barometer is falling slowly or rapidly
you will need to select the first parameter on one line and then the second
parameter on the second line and link them together using the OR group-
ing type.
• Wind Chill and Heat Index formulas used by the streaming data logger
are the same as the May 2005 revision of the Vantage Pro2 console firm-
ware. Wind Chill uses the 10-minute average wind for calculation. Your
console must be powered for at least 10 minutes to utilize a valid wind
chill value.
• Dew point formula is also the same as what the Vantage Pro2 and Van-
tage Pro console uses, but this has not changed from the original firm-
ware version to present.
• Time: Time is entered in 24-hour format. For example, 10 p.m. is entered
as 22:00. Enter a.m. values of 1 a.m. or later as they are, enter p.m. val-
ues of 1 p.m. or later by adding 12 to the hour. 12 a.m. should be entered
as 00:00. 12:01 a.m to 12:59 a.m. should be entered as 00:XX. When
using the between and not-between check types, the Alarm Output data
logger is intelligent enough to handle the midnight rollover. For example,
if you set “IF Time is between 22:00 and 02:00”, the alarm will be active
when the time of day is between 10 p.m. and 2 a.m. including 11 p.m,
Midnight, and 1 a.m. and any times in between. Reversing the entries
will cause the alarm to be active nearly all day excluding the period
around midnight.
• Wind Direction: When using the between and not-between check types,
the Alarm Output data logger is intelligent enough to handle the North
rollover. For example, if you set “IF Wind Direction is between 350° and
10°”, the alarm will be active when the wind direction is between 350°
and 10° including 355°, 0°, and 5° and any directions in between.
Reversing the entries will cause the alarm to be active for most wind
directions excluding those around north.

See the Application Note: “Derived Variables in Davis Weather Products,”
for more detailed information on how derived variables are calculated. This
can be found in the Weather Support section of the Davis Instruments web
site: http://www.davisnet.com.