Campbell CR10XTCR User manual

INSTRUCTION MANUAL
CR10XTCR
Thermocouple Reference
Revision: 1/03
Copyright (c) 1995-2003
Campbell Scientific, Inc.

Warranty and Assistance
The CR10XTCR THERMOCOUPLE REFERENCE is warranted by
CAMPBELL SCIENTIFIC, INC. to be free from defects in materials and
workmanship under normal use and service for twelve (12) months from date of
shipment unless specified otherwise. Batteries have no warranty. CAMPBELL
SCIENTIFIC, INC.'s obligation under this warranty is limited to repairing or
replacing (at CAMPBELL SCIENTIFIC, INC.'s option) defective products.
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defective products to CAMPBELL SCIENTIFIC, INC. CAMPBELL
SCIENTIFIC, INC. will return such products by surface carrier prepaid. This
warranty shall not apply to any CAMPBELL SCIENTIFIC, INC. products
which have been subjected to modification, misuse, neglect, accidents of
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i
CR10XTCR Table of Contents
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1. General........................................................................1
1.1 Specifications............................................................................................1
2. Accuracy — Temperature Sensor .............................1
3. Installation and Wiring ...............................................2
4. Programming ..............................................................3
5. Instruction 11 Details..................................................4
6. Electrically Noisy Environments ...............................6

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1
CR10XTCR Thermocouple Reference
1. General
The Model CR10XTCR Probe contains a thermistor for measuring temperature
and is used as a reference temperature for thermocouples measured with the
CR10X. It is installed between the two terminal stripes in the wiring panel.
After all the thermocouples are wired, the wiring panel cover is installed to
minimize temperature gradients on the terminal strip.
1.1 Specifications
Temperature Measurement Range: -35°to +50°C
Thermistor Interchangeability Error: Typically <±0.2°C over 0°C to 60°C ±0.4
@ -35°C.
Polynomial Linearization Error: <±0.5°C over -35°C to +50°C.
2. Accuracy — Temperature Sensor
The overall probe accuracy is a combination of the thermistor's
interchangeability specification, the precision of the bridge resistors, and the
polynomial error. In a "worst case" all errors add to an accuracy of ±0.4°C
over the range of -24°to 48°C and ±0.9°C over the range of -38°C to 53°C.
The major error component is the interchangeability specification of the
thermistor, tabulated in Table 1. For the range of 0°to 50°C the
interchangeability error is predominantly offset. The bridge resistors are 0.1%
tolerance with a 10 ppm temperature coefficient. Polynomial errors are
tabulated in Table 2 and plotted in Figure 1.
TABLE 1. Thermistor Interchangeability
Specification
Temperature (°C) Temperature Tolerance (±°C)
−40 0.40
−30 0.40
−20 0.32
−10 0.25
0 to +50 0.20
TABLE 2. Polynomial Error
-40 to +56 <±1.0°C
-38 to +53 <±0.5°C
-24 to +48 <±0.1°C

CR10XTCR Thermocouple Reference
2
FIGURE 1. Error Produced by Polynomial Fit to Published Values
3. Installation and Wiring
The wiring diagram for the CR10XTCR is shown in Figure 1. The probe
requires a single-ended analog input channel and an excitation channel. After
the CR10XTCR and thermocouple are connected to the datalogger, install the
wiring panel cover (Figure 2 and 3).
CR10XTCR
LT#343403
FIGURE 2. Wiring Diagram
Analog Ground;
Clear (AG)
Switched
Excitation;
Black (E3)
Single-Ended Input; Red (1H)

CR10XTCR Thermocouple Reference
3
CS I/0
CR10X WIRING PANEL
MADE IN USA
WIRING
PANEL NO.
G 12V
POWER
IN
SE
DEF
SE
DEF
EARTH
CROUND
GGHLAG HLAG E3 AG GG
LAG H
4
785
910 6
11 12
AG GGG
SW 12V CTRL
SW 12V
GGHLAG HLAG E3 AG G
LAG H
1
122
343
56
GGHLAG HLAG E3 12V12V
LAG HSDM
LOGAN, UTAH
FIGURE 3. Wiring Panel, CR10XTCR, and Wiring Panel Cover
SE
DIFF GGH L
12
1AG H L AG H L AG E1 AGE2 G
34
256 3
SE
DIFF GGH L
78
4AG H L AG H L AG E3 AGG G
910
511 12 6
P1 G P2 G C8 C7
5V 5V G G
SW
SW 12
Logan, Utah
EARTH
GROUND
CR10XTCR
LT#343403
TYPETTHERMOCOUPLE
Clear
Red
Black
FIGURE 4. CR10XTCR Installed on the CR10X Wiring Panel
4. Programming
Instruction 11 is used to measure the CR10XTCR. Instruction 11 provides AC
excitation, makes a single ended voltage measurement, and calculates
temperature with a fifth order polynomial. A multiplier of 1.0 and an offset of
0.0 yields temperature in Celsius. For Fahrenheit, use a multiplier of 1.8 and an
offset of 32.
The reference temperature for thermocouples must be in
degrees Celsius.
CAUTION
Clear
Black
TYPE T THERMOCOUPLE
Red

CR10XTCR Thermocouple Reference
4
EXAMPLE 1. Sample CR10X Instructions
01: Temp 107 Probe (P11)
01: 1 Rep
02: 1 IN Chan
03: 3 Excite all reps w/EXchan 3
04: 15* Loc [:Ref_Temp]
05: 1 Mult
06: 0 Offset
* Proper entries will vary with program and input location.
5. Instruction 11 Details
Understanding the details in this section are not necessary for general operation
of the CR10XTCR with Campbell Scientific's dataloggers.
Instruction 11 outputs a precise 2 VAC excitation and measures the voltage drop due to
the sensor resistance (Figure 5). The thermistor resistance changes with temperature.
Instruction 11 calculates the ratio of voltage measured to excitation voltage (Vs/Vx)
which is related to resistance, as shown below:
Vs/Vx = 1000/(Rs+249000+1000)
where Rs is the resistance of the thermistor.
See the measurement section of the datalogger manual for more information on
bridge measurements.
Instruction 11 then calculates temperature using a fifth order polynomial
equation correlating Vs/Vx with temperature. The polynomial coefficients are
given in Table 3. The polynomial input is (Vs/Vx)*800. Resistance and
datalogger output at several temperatures are shown in Table 4.
Black
Red
Clear
FIGURE 5. CR10XTCR Reference Temperature Schematics

CR10XTCR Thermocouple Reference
5
TABLE 3. Temperature, Resistance, and
Datalogger Output
Temperature °C Resistance OHMS Output °C
-40.00 4067212 -39.18
-38.00 3543286 -37.55
-36.00 3092416 -35.83
-34.00 2703671 -34.02
-32.00 2367900 -32.13
-30.00 2077394 -30.18
-28.00 1825568 -28.19
-26.00 1606911 -26.15
-24.00 1416745 -24.11
-22.00 1251079 -22.05
-20.00 1106485 -20.00
-18.00 980100 -17.97
-16.00 869458 -15.95
-14.00 772463 -13.96
-12.00 687276 -11.97
-10.00 612366 -10.00
-8.00 546376 -8.02
-6.00 488178 -6.05
-4.00 436773 -4.06
-2.00 391294 -2.07
0.00 351017 -0.06
2.00 315288 1.96
4.00 283558 3.99
6.00 255337 6.02
8.00 230210 8.04
10.00 207807 10.06
12.00 187803 12.07
14.00 169924 14.06
16.00 153923 16.05
18.00 139588 18.02
20.00 126729 19.99
22.00 115179 21.97
24.00 104796 23.95
26.00 95449 25.94
28.00 87026 27.93
30.00 79428 29.95
32.00 72567 31.97
34.00 66365 33.99
36.00 60752 36.02
38.00 55668 38.05
40.00 51058 40.07
42.00 46873 42.07
44.00 43071 44.05
46.00 39613 46.00
48.00 36465 47.91
50.00 33598 49.77
52.00 30983 51.59
54.00 28595 53.35
56.00 26413 55.05
58.00 24419 56.70
60.00 22593 58.28

CR10XTCR Thermocouple Reference
6
TABLE 4. Polynomial Coefficients
Coefficient Value
C0 -53.4601
C1 90.807
C2 -83.257
C3 52.283
C4 -16.723
C5 2.211
6. Electrically Noisy Environments
AC power lines can be the source of electrical noise. If the datalogger is in an
electronically noisy environment, the CR10XTCR temperature measurement
should be measured with the AC half bridge (Instruction 5) with the 60 Hz
rejection integration option on the CR10X (see Section 13 of the datalogger
manual for more information on noise). Instruction 11's fast integration will not
reject 60 Hz noise.
Example 2. Sample CR10X Instructions Using AC Half Bridge
01: AC Half Bridge (P5)
01: 1 Rep
02: 22 7.5 mV 60 Hz rejection Range
03: 1 IN Chan
04: 3 Excite all reps w/EXchan 3
05: 2000 mV Excitation
06: 15* Loc [:Ref_Temp]
07: 800 Mult
08: 0 Offset
02: Polynomial (P55)
01: 1 Rep
02: 15* X Loc Air Temp
03: 15* F(X) Loc [:Ref_Temp]
04: -53.46 C0
05: 90.807 C1
06: -83.257 C2
07: 52.283 C3
08: -16.723 C4
09: 2.211 C5
* Proper entries will vary with program and input location assignments.

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