National Instruments Corporation SC-207 Series, User Manual

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SC-2070 Board Chapter 2
SC-207X Series User Manual 2-20 © National Instruments Corporation
Table 2-4. NBS Polynomial Coefficients
Type E J K R S T
Temp.
-100
°
to 1,000
°
C 0
°
to 760
°
C 0
°
to 1,370
°
C 0
°
to 1,000
°
C 0
°
to 1,750
°
C -160
°
to 400
°
C
Range
±
0.5
°
C
1
±
0.1
°
C
1
±
0.7
°
C
1
±
0.5
°
C
1
±
1
°
C
1
±
0.5
°
C
1
a
0
0.104967248 -0.048868252 0.226584602 0.263632917 0.927763167 0.100860910
a
1
17189.45282 19873.14503 24152.10900 179075.491 169526.5150 25727.94369
a
2
-282639.0850 -218614.5353 67233.4248 -48840341.37 -31568363.94 -767345.8295
a
3
12695339.5 11569199.78 2210340.682 1. 10 8990730663 78025595.81
a
4
-448703084.6 -264917531.4 -860963914.9 -4. 12 -1. 12 -9247486589
a
5
1. 10 2018441314 4. 10 7. 14 1. 14 6. 11
a
6
-1. 11 -1. 12 -7. 16 -1. 16 -2. 13
a
7
1. 12 1. 13 3. 18 6. 17 3. 14
a
8
-9. 12 -6. 13 -8. 19 -1. 19
a
9
2. 13 1. 20
1
The accuracies shown apply only to the polynomial and do not take into consideration errors introduced by
the SC-2070 board, the MIO-16 board, or the thermocouple itself.
These polynomials are accurate only within the temperature ranges specified. Also, all terms must be
included to achieve the specified accuracy.
To avoid the long computation time required for these high-order polynomials, the operating range of a
thermocouple can be subdivided into several smaller ranges. Each of the smaller ranges can then be
approximated by a much lower order polynomial, such as the polynomial in Formula 2-6. Further
examples of polynomials, including lower-order polynomials for subdivided temperature ranges, can
be found in NIST Monograph 175, Temperature-Electromotive Force Reference Functions and Tables
for the Letter-Designated Thermocouple Types Based on the ITS-90 (National Institute of Standards
Technology, Gaithersburg, MD 20899).