Campbell Scientific HMP35C Temperature and RH Sensor User Manual
Page 8
HMP35C TEMPERATURE AND RH PROBE
6
Example 2. Sample CR10(X) Program measuring HMP35C Temperature
using DC Half Bridge with Delay
;Measure the HMP35C thermistor.
;
01:
Excite-Delay (SE) (P4)
1:
1
Reps
2:
2
7.5 mV Slow Range
;CR500 (7.5 mV); CR23X (10 mV); 21X, CR7 (15 mV)
3:
3
SE Channel
;Orange wire (SE 3), White wire (AG)
4:
1
Excite all reps w/Ex 1
;Black wire (EX 1)
5:
2
Delay (units 0.01 sec)
6: 2000
mV Excitation
;CR500, CR23X (2000 mV); 21X, CR7 (4000 mV)
7:
1
Loc [ T_C ]
8:
0.4
Mult
;CR500, CR23X (0.4); 21X, CR7 (0.2)
9:
0
Offset
;Compute the temperature in degrees Celsius.
;
02:
Polynomial (P55)
1:
1
Reps
2:
1
X Loc [ T_C ]
3:
1
F(X) Loc [ T_C ]
4:
-53.46
C0
5:
90.807 C1
6:
-83.257 C2
7:
52.283 C3
8:
-16.723 C4
9:
2.211 C5
;Apply the temperature multiplier.
;
03:
Z=X*F (P37)
1:
1
X Loc [ T_C ]
2:
1
F
;See Table 4 for alternate multipliers
3:
1
Z Loc [ T_C ]
;Apply the temperature offset.
;
04:
Z=X+F (P34)
1:
1
X Loc [ T_C ]
2:
0
F
;See Table 4 for alternate offsets
3:
1
Z Loc [ T_C ]
;Turn the HMP35C on.
;
05:
Do (P86)
1:
41
Set Port 1 High
;Yellow wire (C1)
;Pause 150 milliseconds, before making the measurement, so the
;probe can stabilize on the true relative humidity.
;
06:
Excitation with Delay (P22)
1:
1
Ex Channel
2:
0
Delay W/Ex (units = 0.01 sec)
3:
15
Delay After Ex (units = 0.01 sec)
4:
0
mV Excitation