Campbell Scientific HFP01SC HFP01SC Hukseflux Self-Calibrating Soil Heat Flux - Page 12

Model HFP01SC Self-Calibrating Soil Heat Flux Plate 6.2 Wiring Connections to Campbell Scientific dataloggers are given in FIGURE 6-1, TABLE 6-1, and TABLE 6-2. The output of the HFP01SC can be measured using a single-ended analog measurement (VoltSE() or Instruction 1), however, a differential analog measurement (VoltDiff() or Instruction 2) is recommended. The wiring convention is that the white wire is positive with respect to the green wire, when energy is flowing through the transducer from the side with the text "this side up" to the other side. NOTE The switched 12 Vdc port can source enough current to calibrate four HFP01SC plates. If additional HFP01SC plates are needed, an external relay is required to power the additional plates (see example 4). For dataloggers without a SW12V output (CR7X, 21X and CR10), a relay (A21REL-12) is required for the in-situ calibration (see Example 4). 6.3 Programming The HFP01SC has a nominal calibration of 15 W m-2 mV-1. Each sensor is accompanied by a calibration certificate. Each sensor also has a unique calibration label on it. The label is located on the pigtail end of the sensor leads. 6.3.1 Example 1. Sample CR3000 Program Using a Differential Measurement Instruction TABLE 6-3 provides the wiring for Example 1. TABLE 6-3. Wiring for Example 1 Description Sensor Signal #1 Sensor Signal Reference #1 Shield #1 Sensor Signal #2 Sensor Signal Reference #2 Shield #2 Sensor Signal #3 Sensor Signal Reference #3 Shield #3 Sensor Signal #4 Sensor Signal Reference #4 Shield #4 Color White Green Clear White Green Clear White Green Clear White Green Clear CR3000 9H 9L 10H 10L 11H 11L 12H 12L 6