Campbell Scientific CMP3 Pyranometer - Manual (Page 9)

CMP3-L Pyranometer
TABLE 4-2. Single-Ended Connections to Campbell Scientific Dataloggers
Color
Description CR9000(X)
CR5000
CR3000
CR1000
CR800
CR510
CR500
CR10(X)
21X
CR7
CR23X
White Signal (+) Single-Ended Analog Single-Ended Analog Single-Ended Analog
Black Signal (-) AG
Shield Shield G
5. Example Programs
This section is for users who write their own datalogger programs. A
datalogger program to measure this sensor can be created using Campbell
Scientific’s Short Cut Program Builder software. You do not need to read this
section to use Short Cut.
Solar radiation can be reported as an average flux density (W m -2 ) or daily
total flux density (MJ m -2 ). The appropriate multipliers are listed in Table 5-1.
Programming examples are given for both average and daily total solar
radiation.
The CMP3-L outputs a low level voltage ranging from 0 to a maximum of up
to 20 mV, in natural light, depending on the calibration factor and radiation
level.
A differential voltage measurement is recommended because it has better noise
rejection than a single-ended measurement. If a differential channel is not
available, a single-ended measurement can be used. The acceptability of a
single-ended measurement can be determined by simply comparing the results
of single-ended and differential measurements made under the same
conditions.
Nearby AC power lines, electric pumps, or motors can be a source of electrical
noise. If the sensor or datalogger is located in an electrically noisy
environment, the measurement should be made with the 60 or 50 Hz rejection
integration option as shown in the example programs.
5.1 Input Range
The output voltage of the CMP3-L is usually between 5 and 20 mV per
1000 Wm
-2 . When estimating the maximum likely value of sensor output a
maximum value of solar radiation of 1100 Wm -2 can be used for field
measurements on a horizontal surface.
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