Campbell Scientific LI200X-L LI-COR Silicon Pyranometer - Manual (Page 9)

LI200X Pyranometer
40.2 to 90.2 Ω
RED
BLACK
WHITE
CLEAR
H
L
AG OR GND
GND
FIGURE 3-1. LI200X Schematic
If a 21X is used to measure the LI200X and powers a 12 VDC
sensor, the current drawn by the 12 VDC sensor may cause a
difference in ground potential between the 21X ground terminals
and the reference ground point in the datalogger. This ground
potential results in an offset on single ended measurements. This
offset can be as large as ± 60 mV. Thus, single ended
measurements should be avoided. The offset does not, however,
affect differential measurements. NOTE
4. Programming
This section is for users who write their own datalogger programs. A
datalogger program to measure the LI200X can be created using the Short Cut
software. You do not need to read the following section to use Short Cut.
Output from the LI200X is 0.2 kWm -2 mV -1 , which is measured by the
datalogger using the differential voltage instruction (VoltDiff in CRBasic or
Instruction 2 in Edlog). Dataloggers that use CRBasic include the CR800,
CR850, CR1000, CR3000, CR500, and CR9000(X). Dataloggers that use
Edlog include the CR510, CR10(X), and CR23X. Both CRBasic and Edlog
are included in PC400 and LoggerNet datalogger support software.
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.
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 4-1.
Programming examples are given for both average and daily total solar
radiation. Negative values should be set to zero before being processed.
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