Campbell Scientific CR7 Measurement and Control System - Manual (Page 73)

SECTION 7. MEASUREMENT PROGRAMMING EXAMPLES
7-5
04: P87 Beginning of Loop
01: 0 Delay
02: 4 Loop Count
05: P33 Z=X+Y
01: 1 X Loc REF TEMP
02: 2-- Y Loc TC temp#1
03: 2-- Z Loc [:TC temp#1]
06: P95 End
PROGRAM B
01: P17 Panel Temperature
01: 1 IN Card
02: 1 Loc [:REF TEMP ]
02: P14 Thermocouple Temp (DIFF)
01: 5 Reps
02: 3 15 mV slow Range
03: 1 IN Card
04: 1 IN Chan
05: 12 Type E (Temp difference)
06: 1 Ref Temp Loc REF TEMP
07: 2 Loc [:TC temp#1]
08: .99253 Mult
09: 0 Offset
If there were additional groups of
thermocouples, the Instructions to measure
them would be inserted here and Parameter 2
in Instruction 87 adjusted accordingly.
03: P87 Beginning of Loop
01: 0 Delay
02: 5 Loop Count
04: P33 Z=X+Y
01: 1 X Loc REF TEMP
02: 2-- Y Loc TC temp#1
03: 2-- Z Loc [:TC temp#1]
05: P95 End
7.7 107 TEMPERATURE PROBE
Instruction 11 is designed to excite and
measure the Campbell Scientific 107 thermistor
probe (or the thermistor portion of the 207
temperature and relative humidity probe) and
convert the measurement into temperature
(oC). In this example, the temperatures are
obtained from three 107 probes. The
measurements are made on single ended
channels 1-3, and the temperatures are stored
in Input locations 1-3.
CONNECTIONS
The black leads from the probes go to excitation
channel 1, the white leads go to ground, and the
red leads go to single ended channels 1, 2, and
3 (high and low sides of differential channel 1
and high side of 2).
PROGRAM
01: P11 Temp 107 Probe
01: 3 Reps
02: 1 IN Card
03: 1 IN Chan
04: 1 EX Card
05: 1 EX Chan
06: 1 Loc [:107 T #1 ]
07: 1 Mult
08: 0 Offset
7.8 207 TEMPERATURE AND RH PROBE
Instruction 12 excites and measures the RH
portion of the Campbell Scientific 207
temperature and relative humidity probe. This
instruction relies on a previously measured
temperature to compute the RH from the probe
resistance. Instruction 12 has the option of
using a single temperature to provide the
compensation reference for several RH probes.
In this example, three probes will be measured;
the temperature of each probe will be measured
and used to provide temperature compensation
for that probe. Instruction 11 is used to obtain
the temperatures of the three probes which are
stored in Input locations 1-3, the RH values are
stored in Input locations 4-6. The temperature
measurements are made on single ended input
channels 1-3, just as in example 7.7. The
program listed below is a continuation of the
program given in example 7.7.
CONNECTIONS
The black leads from the probes are connected
to excitation channel 1, the clear leads are
connected to ground. The red leads are from
the thermistor circuit and are connected to
single ended channels 1-3. The white leads are
from the RH circuit and are connected to single
ended channels 4-6. The correct order must be
maintained when connecting the red and white
leads, i.e., the red lead from the first probe is
connected to single ended channel 1 and the
white lead from that probe is connected to
single ended channel 4, etc.