calculation, set Thermistor Enabled to True and enter the thermistor coefficient A, B, and C values
for Steinhart-Hart conversion. The CRVW3 uses the following equation to convert from
resistance to temperature:
Tc = (1 / (A + B × ln (Rs) + C × (ln (Rs))
3
)) – 273.15
Enable the calculation by setting Calculate Engineering Output to True. Enter a label for the
desired output units in the Engineering Units box. This is a string label for the units of the
calculated output values (for example, mm, ft, kg, kPa, or µε); it does not affect the calculations.
If your sensor manual uses digits as the frequency input for calculating engineering units, set
UseDigits to True. The polynomial used for calculation will be based on digits and temperature;
frequency in Hz will not be used. Conversely, when UseDigits is False, the polynomial used will be
based on frequency (Hz) and temperature; digits are not used.
The following table shows the engineering units polynomial constants and the related terms used
in
Device Configuration Utility
.
Table D-1:
Device Configuration Utility
settings used to set coefficients
Use this
Device Configuration Utility
setting
To set this coefficient
Frequency/Digits squared (second-degree) coefficient
A (first polynomial constant)
Frequency/Digits linear (first-degree) coefficient
B
Constant term
C
Temperature squared (second-degree) coefficient
D
Temperature linear (first-degree) coefficient
E
Hybrid temperature coefficient (Temp × Freq or Temp ×
Digits)
F
When UseDigits is True, the form of the calculation polynomial is:
A ×
d
² + B ×
d
+ C + D ×
t
² + E ×
t
+ F ×
d
×
t
Where:
d
= digits
t
= temperature
A, B, C, D, E, F = user-specified coefficients (constants)
When UseDigits is False, the form of the polynomial is:
A ×
f
² + B ×
f
+ C + D ×
t
² + E ×
t
+ F ×
f
×
t
Where:
CRVW3 3-Channel Vibrating-Wire Data Logger
82
