Campbell Scientific 107-L Temperature Probe - Manual (Page 17)

Model 107 Temperature Probe
TABLE 8-1. 107 Measurement Details
Datalogger
Model
Measurement
Instruction
Excite
mV Result Scaling
Equation
Applied to
Scaled Result
CR800
CR1000
CR3000
CR5000
CRBasic
Therm107()
Steinhart-Hart
(automatically
applied)
CR10
CR10X
CR500
CR510
CR23X
Edlog
Temp(107)(P11) 2000
Vs/Vx
Multiply
by 800 ‡
Fifth-order
polynomial
(automatically
applied)
21X
CR7(X)
Edlog
Temp(107)(P11) 4000
Vs/Vx
Multiply
by 800 ‡
Fifth-order
polynomial
(automatically
applied)
† Fixed series resistance is subtracted before applying Steinhart-Hart.
‡ Multiplier of 800 scales Vs/Vx for the polynomial fit.
TABLE 8-2. Temperature Calculation
CRBasic Dataloggers 1
Therm107() instruction measures the ratio Vs/Vx, calculates the thermistor resistance
Rs, and converts Rs to temperature using the Steinhart-Hart equation 2 :
T = 1 / (A + (B • ln(Rs))) + (C • ((ln(Rs))) ^ 3) – 273.15
where:
T = temperature in Celsius
A = 8.271111E–4
B = 2.088020E–4
C = 8.059200E–8
Edlog Dataloggers 3
Temp(107) (P11) instruction measures the ratio Vs/Vx and coverts it to temperature
using a fifth-order polynomial:
T = C0 + C1•X + C2•X^2 + C3•X^3 + C4•X^4 + C5•X^5
where:
X = (Vs/Vx) • 800
C0 = –53.4601
C1 = 9.0807
C2 = –0.83257
C3 = 0.052283
C4 = –0.0016723
C5 = 0.00002211
See Appendix C, Thermistor Resistance Table.
1 CRBasic dataloggers are CR800, CR1000, CR3000, and CR5000.
2 Coefficients provided by the thermistor manufacturer.
3 Edlog dataloggers are CR10(X), CR500, CR510, CR23X, 21X, and CR7.
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