Campbell-scientific HMP35C Temperature and RH Sensor Instrukcja Użytkownika Pobierz pdf (Strona 6)

HMP35C TEMPERATURE AND RH PROBE

4

4. WIRING

Connections to Campbell Scientific dataloggers

are given in Table 3. The probe is measured by

two single-ended input channels, one for

temperature and one for relative humidity. A

single excitation channel is used for the

temperature measurement.

The number of HMP35C probes that can be

excited by one excitation channel is physically

limited by the number of lead wires that can be

inserted into a single excitation terminal

(approximately 6).

5. EXAMPLE PROGRAMS

This section is for users who write their own

datalogger programs. A datalogger program to

measure this sensor can be created using

Campbell Scientific’s Short Cut Program Builder

software. You do not need to read this section to

use Short Cut.

The temperature is measured using a single-

ended analog measurement and an excitation

channel (Instruction 11). The relative humidity is

measured using a single-ended analog

measurement (Instruction 1). Tables 4 and 5

provide calibration information for temperature

and relative humidity.

CAUTION: Do no turn the HMP35C on

before measuring the thermistor. Doing so

will induce a transient signal spike on the

thermistor leads that will result in an

erroneous temperature measurement.

Always measure the HMP35C temperature

first.

TABLE 4. Calibration for Temperature

Units Multiplier

(degrees mV

-1

)

Offset

(degrees)

Celsius 1 0

Fahrenheit 1.8 32

TABLE 5. Calibration for Relative Humidity

Units Multiplier

(% mV

-1

)

Offset

(%)

Percent 0.1 0

Fraction 0.001 0

TABLE 6. Wiring for Example 1

Description Color CR10(X)

Temperature Orange SE 3 (2H)

Relative Humidity Green SE 4 (2L)

Temperature Signal Reference White AG

Temperature Excitation Black E1

Power Control Yellow C1

Power Red 12 V

RH Signal, Power, & Control Reference Purple AG

Shield Clear G

Example 1. Sample CR10(X) Program measuring HMP35C

Temperature and Relative Humidity

;Measure the HMP35C temperature.

;

01: Temp (107) (P11)

1: 1 Reps

2: 3 SE Channel

;Orange wire (SE 3), White wire (AG)

3: 1 Excite all reps w/E1

;Black wire (EX 1)

4: 1 Loc [ T_C ]

5: 1 Mult

;See Table 4 for alternate multipliers

6: 0 Offset

;See Table 4 for alternate offsets

;Turn the HMP35C on.

;

02: Do (P86)

1: 41 Set Port 1 High

;Yellow wire (C1)

1 2 3 4 5 6 7 8 9 10 11 ... 15 16

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