LI-COR LI-7500, Инструкция по эксплуатации

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Section 3
3-24 Setup and Operation
The LI7500 program is used to enter slope and offset data for auxiliary sensors, via the Inputs
Tab described above. The software will only accept auxiliary coefficients for one external
sensor at a time. Depending on the measurements that you are taking, you will need to decide
which external sensor (if any) you want to use. As emphasized before, the temperature and
pressure sensors do not need to be very accurate for output of density data (e.g. mmol m
-3
).
Concentration data (e.g. ppm), however, requires much more accurate measurement of
temperature and pressure. The LI-7500 does not allow output of concentration in your data
stream. However, the Calibration Tab will allow you to view concentration data based on your
Input Tab selections. To calculate concentration from density data would require post-
processing using the equations found in Table 2-21.
The LI-7500 auxiliary input is a 12-bit differential input. The input range is 0 to +4096 mV.
Since the input is uni-polar (e.g. measures only positive signals) users should note the polarity
of their sensor output signal when connecting to this input channel. The physical connections
from a customer supplied sensor to the LI-7500 auxiliary input would consist of using the
Analog Input Cable (Part# 392-05621, in the spares kit). Appendix B details the differential
input connections.
Auxiliary Input Cable Color Customer Sensor
Ground Black Shield
Differential In (+) Red Positive Signal (e.g. 0 to +5V)
Differential In (-) Brown Sensor Reference or Signal Ground (e.g. 0V)
This cable can be soldered onto the output leads of a customer provided sensor. The
remaining conductors (Blue, Gray and White) for the auxiliary input are not used in this
mode.