Campbell Scientific LI200X LI200X-L LI-COR Silicon Pyranometer - Page 9

LI200X Pyranometer RED H 40.2 to 90.2 Ω BLACK L WHITE AG OR GND CLEAR GND FIGURE 3-1. LI200X Schematic NOTE 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. 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-2mV-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. 5