5
CONNECTING TO A LOGGER
MPS-2 & MPS-6
The water potential in kilopascals is the first number output by the
sensor. The second number is temperature in Celsius.
The SDI-12 communication protocol is supported in Campbell Sci-
entific data loggers like the CR10X, CR200, CR1000, CR3000, etc.
Direct SDI-12 communication is supported in the “Terminal Emu-
lator” mode under the “Tools” menu on the “Connect” screen. De-
tailed information on setting the address using CSI data loggers can
be found on our website at
http://www.decagon.com/support
.
5.5
Installing the Sensors
Because the MPS-2 and MPS-6 measure water potential, they are
not as sensitive to air gaps or soil disturbance as water content sen-
sors. The MPS-2 and MPS-6 need good hydraulic contact with the
surrounding soil. The preferred method for installing the sensor is to
take some native soil, wet it, and pack it in a ball around the entire
sesnor, making sure that the moist soil is in contact with all surfaces
of the ceramic. The sensor and moist soil are then packed into the
soil at the desired depth.
In sandy soils, the soil may not adhere to the sensor even when wet.
In this case the sensor can be packed into soil at the bottom of a
hole dug to the desired installation depth. Again, take care to pack
the sandy soil around the sensor with good contact to all ceramic
surfaces.
After installing the sensor and moist soil, the hole that was exca-
vated to bury the sensor at depth should be back-filled with care
taken to pack the soil back to its native bulk density. Leave at least
six inches of sensor cable beneath the soil before bringing the cable
to the surface. The cable should never be bent in a tight radius as it
leaves the sensor body. At least four inches of cable should exit the
sensor body in a straight line before bending the cable.
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