SM150T User Manual 1.0
Appendix 2:
51
GP1, GP2 and DL6 loggers
The ‘SM150T Temperature’ sensor type in DeltaLINK performs the supply
current correction.
DL2e Logger
The linearization table for the ‘S3T’ sensor code (‘SM150T Temperature’)
provides supply current correction for the
SMSC/lw-05
5m logger cable
ONLY.
Extension cables and other cable lengths
Create your own custom sensor type(s) and linearization tables as described
in
Ls2Win
Help topic, How to… ‘Add or modify a sensor type in the sensor
library’.
Enter corrected resistance values (R) for each linearization table point:
R = R5 + (0.059 x Lex) kΩ (See footnote
10
)
Or
R = R5 + (0.9 x Rc
– 0.297) kΩ
where
R5 = value supplied in the table for the ‘SM150T Temp, 5m’ sensor type.
Lex = length of extension cable, excluding the 5m of
SMSC/lw-05
cable.
Rc = total cable resistance, including resistance of
SMSC/lw-05
cable, if fitted.
Other loggers
If your logger can be programmed so that the soil moisture and temperature
readings can be taken sequentially (i.e. the sensor is not powered during the
temperature reading), then the temperature can be obtained directly from the
response curve on page 50.
Otherwise, correct the resistance reading before applying the response curve.
You need to know the resistance of the Power 0V wire in the SM150T cable
(Rc) and establish whether your logger uses voltage or current excitation for
resistance measurement.
10
Note: This equation only applies to Delta-T SM150T cables
