Ov5.2 sample program 2 – Campbell Scientific CR10X Measurement and Control System User Manual
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CR10X OVERVIEW
OV-16
OV5.2 SAMPLE PROGRAM 2
EDLOG Listing Program 2:
*Table 1 Program
01:
5.0
Execution Interval (seconds)
1: Internal Temperature (P17)
1:
1
Loc [ CR10XTemp ]
2: Thermocouple Temp (DIFF) (P14)
1:
1
Reps
2:
1
± 2.5 mV Slow Range
3:
5
DIFF Channel
4:
1
Type T (Copper-Constantan)
5:
1
Ref Temp Loc [ CR10XTemp ]
6:
2
Loc [ TCTemp ]
7:
1.0
Mult
8:
0.0
Offset
3: If time is (P92)
1:
0
Minutes (Seconds --) into a
2:
60
Interval (same units as above)
3:
10
Set Output Flag High
4: Real Time (P77)
1:
110
Day,Hour/Minute
5: Average (P71)
1:
2
Reps
2:
1
Loc [ CR10XTemp ]
6: If time is (P92)
1:
0
Minutes (Seconds --) into a
2:
1440
Interval (same units as above)
3:
10
Set Output Flag High
7: Real Time (P77)
1:
110
Day,Hour/Minute
8: Maximize (P73)
1:
1
Reps
2:
10
Value with Hr-Min
3:
2
Loc [ TCTemp ]
9: Minimize (P74)
1:
1
Reps
2:
10
Value with Hr-Min
3:
2
Loc [ TCTemp ]
10:
Serial Out (P96)
1:
71
SM192/SM716/CSM1
This second example is more representative of a
real-life data collection situation. Once again the
internal temperature is measured, but it is used
as a reference temperature for the differential
voltage measurement of a type T (copper-
constantan) thermocouple; the CR10X should
have arrived with a short type T thermocouple
connected to differential channel 5.
When using a type T thermocouple, the copper
lead (blue) is connected to the high input of the
differential channel, and the constantan lead
(red) is connected to the low input.
A thermocouple produces a voltage that is
proportional to the difference in temperature
between the measurement and the reference
junctions.
To make a thermocouple (TC) temperature
measurement, the temperature of the reference
junction (in this example, the approximate panel
temperature) must be measured. The CR10X
takes the reference temperature, converts it to
the equivalent TC voltage relative to 0
o
C, adds
the measured TC voltage, and converts the
sum to temperature through a polynomial fit to
the TC output curve (Section 13.4).
The internal temperature of the CR10X is not a
suitable reference temperature for precision
thermocouple measurements. It is used here
for the purpose of training only. To make
thermocouple measurements with the CR10X,
purchase the Campbell Scientific Thermocouple
Reference, Model CR10TCR (Section 13.4) and
make the reference temperature measurement
with Instruction 11.
Instruction 14 directs the CR10X to make a
differential TC temperature measurement. The
first parameter in Instruction 14 is the number of
times to repeat the measurement. Enter 1,
because in this example there is only one
thermocouple. If there were more than 1 TC,
they could be wired to sequential channels, and
the number of thermocouples entered for
repetitions. The CR10X would automatically
advance through the channels sequentially and
measure all of the thermocouples.
Parameter 2 is the voltage range to use when
making the measurement. The output of a type
T thermocouple is approximately 40 microvolts
per degree C difference in temperature between
the two junctions. The
±
2.5 mV scale will