Campbell Scientific 107 107-L Temperature Probe - Page 13

Model 107 Temperature Probe 7.2.1 CRBasic 7.2.2 Edlog The Therm107() measurement instruction programs CRBasic dataloggers (CR800-series, CR1000, CR3000, CR5000) to measure the 107 probe. It supplies a 2500 mV excitation, makes a half-bridge resistance measurement, and converts the result to temperature using the Steinhart-Hart equation (see Section 8.2, Measurement and Output Linearization, for more information): Therm107(Dest,Reps,SEChan,VxChan,SettlingTime,Integ,Mult,Offset) Variations: • Temperature reported as °C - set Mult to 1 and Offset to 0 • Temperature reported as °F - set Mult to 1.8 and Offset to 32 • Ac mains noise filtering - set Integ to _60Hz or _50Hz (see Section 8.3, Electrically Noisy Environments) • Compensate for long cable lengths - Set SettlingTime to 20000 (see Section 8.4, Long Cable Lengths) The Temp(107) (P11) measurement instruction programs Edlog dataloggers (CR10(X), CR510, CR500, CR23X, 21X, and CR7(X)) to measure the 107 probe. It makes a half-bridge resistance measurement and converts the result to temperature using a fifth-order polynomial (see Section 8.2, Measurement and Output Linearization, for more information): 1: Temp (107) (P11) 1:1 Reps 2:1 SE Channel 3:21 Excite all reps w/E1, 60Hz, 10ms delay 4:1 Loc [ T107_C ] 5:1.0 Multiplier 6:0.0 Offset NOTE Parameter 3: Ex Channel Option specifies the excitation channel to be used for the measurement. Option 21, which applies a 60 Hz noise filter to the measurement, is normally used. See the Edlog help system for information about other options. Variations: • Temperature reported as °C - set Multiplier to 1 and Offset to 0 • Temperature reported as °F - set Multiplier to 1.8 and Offset to 32 • Ac mains noise filtering - see Section 8.3, Electrically Noisy Environments • Compensate for long cable lengths - see Section 8.4, Long Cable Lengths 7.3 Air Temperature Installation For air temperature measurements, locate probes over an open level area at least 9 m (EPA) in diameter. The surface should be covered by short grass or the natural earth surface where grass does not grow. Probes should be located at a distance of at least four times the height of any nearby obstruction, and at least 30 m (EPA) from large paved areas. Sensors should be protected from thermal radiation, and adequately ventilated. 7