TheCR10XTCR THERMOCOUPLE REFERENCE is warranted by
CAMPBELL SCIENTIFIC, INC. to be free from defects in materials and
workmanship under nor mal use and service for twelve (12) months from date of
shipment unless specifi ed 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.
The customer shall assume all costs of removing, reinstalling, and shipping
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
nature, or shipping damage. This warranty is in lieu of all other warranties,
expressed or implied, including warranties of merchantability or fitness for a
particular purpose. CAMPBELL SCIENTIFIC, INC. is not liable for special,
indirect, incidental, or consequential damages.
Products may not be returned without prior authorization. The following
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served by Campbell Scientific, Inc. directly. Affiliate companies handle repairs
for customers wi thin their territories. Please visi t www.campbellsci.com to
determine which Campbell Scientific company serves your country. To obtain
a Returned Materials Authorization (RMA), contact CAMPBELL
SCIENTIFIC, INC., phone (435) 753-2342. After an applications engineer
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CR10XTCR Table of Contents
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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:
Thermistor Interchangeability Error:
Polynomial Linearization Error:
-35° to +50°C
Typically <±0.2°C over 0°C to 60°C ±0.4
@ -35°C.
<±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
Temperature (°C)
Tolerance (±°C)
−40
−30
−20
−10
0 to +500.20
TABLE 2. Polynomial Error
-40 to +56
-38 to +53
-24 to +48
<±1.0°C
<±0.5°C
<±0.1°C
0.40
0.40
0.32
0.25
1
CR10XTCR Thermocouple Reference
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).
Analog Ground;
Clear (AG)
CR10XTCR
LT#343403
Single-Ended Input; Red (1H)
FIGURE 2. Wiring Diagram
Switched
Excitation;
Black (E3)
2
CR10XTCR Thermocouple Reference
SE
DIFF
G
GH L
12
1
AG H L AG H L AG E1 AG E2 G
34256
3
SE
DIFF
G
GH L
78
4
AG H L AG H L AG E3 AG G G
910511 12
6
P1 G P2 G C8 C7
5V 5V GG
SW
SW 12
Logan, Utah
EARTH
GROUND
LOGAN, UTAH
SE
DEF
G
7
G
4
H
8
L
9
CROUND
EARTH
SE
DEF
AG
5
10
H
L
11
G
G
H
AG
1
1
2
L
AG
H
6
H
12
L
AG
3
2
L
E3
4
AG
AG
5
H
G
3
L
G
6
AG
E3
AG
AG
G
SW 12V CTRL
G
G
SW 12V
G
G
G
H
L
AG
H
L
AG
H
CR10X WIRING PANEL
L
SDM
AG
E3
12V
12V
PANEL NO.
MADE IN USA
G 12V
POWER
IN
CS I/0
WIRING
FIGURE 3. Wiring Panel, CR10XTCR, and Wiring Panel Cover
4. Programming
CAUTION
Red
Red
CR10XTCR
LT#343403
TYPETTHERMOCOUPLE
TYPE T THERMOCOUPLE
FIGURE 4. CR10XTCR Installed on the CR10X Wiring Panel
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.
* 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
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