Owner's Manual

Evapotranspiration (ET) is the total discharge of water by direct
evaporation from soil and rock surfaces, and transpiration from
growing plants. Sentinel has extensive provisions for irrigation
based on ET.
ET information can be obtained from one of four sources. The
source must be specified in the Software Configuration screen
as shown at the right. (Refer to Chapter 3 for additional
information.) ET data can be manually entered in a field unit or in
the central database. An ET gauge and a rain gauge can be
connected to a field unit, or periodic ET values in inches can be
recorded by a GroWeather station or a Campbell Weather
Station.
If ET values are to be entered manually, the first option, Copy default ET from
Unit # should be selected. Daily ET values must be entered in the field unit
specified here, or entered in the ET Report screen for that unit and sent to that unit.
Once the daily value is stored in the default unit, it is available for Sentinel to read
from the database at the end of the day and transmit to all other units.
If an ET Gauge is connected to a field unit, the second option should be selected.
The unit code for that unit is entered here. That field unit will be polled to transmit
ET to other units. If a rain gauge is also connected, daily rainfall measurements can
be used in conjunction with ET.
If you have a GroWeather Station, select the third option under the ET / Rain
Source. A GroWeather Station must be selected for the current system in the
System / Group Maintenance screen, as shown in Chapter 3. The
GroWeatherLink software must poll the weather station from your central computer,
the same computer where Sentinel is installed. Sentinel will read and sum the ET
values for the last available day from the GroWeatherLink database and transmit the
last daily total to all field controllers in the current system.
GroWeather Station
ET Gauge
Manual Entry
Chapter 10 : ET Based Watering
10 - 22
Toro Sentinel Central Software User’s Guide