Campbell Scientific LI200X LI200X-L LI-COR Silicon Pyranometer - Page 15

Appendix A. LI200S Pyranometer A.1 LI200S Pyranometer LI200S pyranometers have a 100 ohm shunt resistor built into the cable. They can be directly measured by Campbell Scientific dataloggers. The input range and multipliers vary from one pyranometer to another. See Sections A.3 and A.4 for calculating the proper input range and multiplier. A.1.1 Wiring The red lead is connected to the high side (H) of a differential input channel and the black lead to the corresponding low side (L). On the CR10 a jumper wire is installed between the low side and analog ground (AG). The clear lead is connected to ground (G). On the 21X the jumper wire is installed between the low side and ground (G) and the clear lead is also connected to ground (G). The measurement is then made with Instruction 2 (see Section 4). A.2 Unmodified Pyranometers Pyranometers that do not have variable or fixed shunt resistors built into the cable can still be measured by Campbell Scientific dataloggers. This is done by wiring in a 100 Ω shunt resistor directly onto the datalogger wiring panel. The input range and multipliers vary from one pyranometer to another. See Sections A.3 and A.4 for calculating the proper input range and multiplier. A.2.1 Wiring Signal positive is connected into the high side(H) of a differential input channel and signal negative to the corresponding low side (L). A jumper wire is installed between the low side (L) and analog ground (AG) on the CR10 wiring panel or ground on the 21X. A 100 Ω 1% resistor (P/N 191) is installed on the wiring panel between the high and low sides the measurement channel. The measurement is then made with Instruction 2 (see Section 5). FIGURE A.2-1. Unmodified Pyranometer Wiring Schematic A-1