Campbell Scientific PWS100 Present Weather Sensor - Manual (Page 90)

Section 8. Functional Description
8.3.1 Using a CS215-PWS on the PWS100
The CS215-PWS temperature and RH probe should be connected directly to
one of the free SDI-12 connectors at the base of the DSP enclosure as shown in
Figure 6-5. The CS215 is mounted inside a radiation shield and needs to be
mounted away from the actual detection volume of the PWS100 in order to
avoid any turbulence effects in the volume that could give rise to inaccuracies
in the measurement of speed and size of particles. The bracket for the
CS215-PWS should therefore point in the opposite direction to the mounted
PWS100. Adding a CS215 improves the precipitation type algorithm by adding
three further parameters, temperature, relative humidity and wet bulb
temperature. Though wetbulb temperature is derived from other parameters,
there is plenty of evidence showing its relationship with the precipitation type
and thus it becomes a useful parameter within itself. If no CS215-PWS is
connected then an internal, less accurate temperature measurement is used, and
the sensor assumes the relative humidity is 100%. The removal of the
CS215-PWS does not prevent the unit from working, but can lead to less
accurate particle classifications.
The CS215 should be “recalibrated” at the recommended
interval, normally every year, to ensure accurate measurements
from it and the PWS100. In the case of the CS215 this is most
easily achieved by replacing the sensor element in situ with a
new one. NOTE
8.3.2 Using Other Sensors on the PWS100
Starting from operating system version 4, the PWS100 can accept temperature
and humidity values sent from the controlling system, which might have access
to data from another air temperature and relative humidity sensor. This is
enabled by selected the remote TRH sensor type in the configuration menu and
the remote system sending the data (space separated) using the RSENSOR
terminal command.
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