Dynamax Inc
30
3.3.3 Soil Temperature sensor (109)
The 109 is designed to measure the temperature of air, water, or soil. For air temperature
measurements, the 41303-5A solar radiation shield is typically used to house the probe, while
limiting solar loading on the sensor. The temperature probe can also be buried or submerged to 50
feet. The probe is not weighted for submergence (ie, it will float), so the installer should plan to
add a weighting system or secure the probe to a fixed, submerged object, such as a piling. The 109
has a measurement temperature range of -50° to +70°C and outputs a full scale range of 0 to 2.2
Volts. Recommended lead lengths are 25, 50, 75, and 100 feet, although the 109 may be ordered
with lead lengths up to 1000 ft. Therm109 instruction is used to excite the sensor(s), measure the
sensor output voltage and calculate output in degrees C.
Therm109 (Dest, Reps, SEChan, ExChan, Mult, Offset)
3.3.4 Soil Moisture Sensor (SM300)
SM300 soil moisture sensor measures volumetric soil moisture content by the principle of
dielectric constant of the medium changes with water content. The change in dielectric
constant is measured in mV DC voltage. Weather station reads the DC voltage and converts to
volumetric soil content in %. Soil moisture sensor SM300 is wired to the InteliMet-Advantage
weather station. Select the location for installing the SM300 sensor, usually close to the
sprinkler fall area or under the drip nozzle. Push the sensor in to the soil until the rods are fully
covered. Route wire to the station and secure it from any damage. Based on the type of soil in
which measurements are made, identify the constants slope and offset parameters. Enter these
values in CR200 program to calculate soil moisture for either organic or mineral soil using
polynomial equation.
Linear constants
Slope
Offset
Mineral Soil
0.059788
3.87
Organic Soil
0.066439
6.995
Color
Function
CR200 channel wiring
Black
Excitation
Switched Excitation
Red
Signal
Single-ended channel
Purple
Signal Ground
SGnd
Clear/ Shield
Shield
SGnd
SM300 Wiring
Color
Function
CR200 channel wiring
Red
Excitation Switched Battery
White
Signal
Single-ended channel
Shield
Ground
SGnd
For custom sensors added to CR200 refer to
the application notes supplied with the
system/ sensor manual
