Campbell HMP 35A Manuel d'instructions télécharger pdf (Page 21)

HMP155A Temperature and Relative Humidity Probe

7.3 Datalogger Programming

The temperature and relative humidity signals from the HMP155A can be

measured using a single-ended analog measurement or a differential analog

measurement.

Use a single-ended analog measurement when the HMP155A signal lead

length is less than 6.1 m (20 ft) or if the probe will be turned on and off under

datalogger control between measurements. For lead lengths greater than 6.1 m

(20 ft) or when the probe will be continuously powered, use a differential

analog measurement. For a discussion on errors caused by long lead lengths

see Section 7.4, Long Lead Lengths.

HMP155A sensors purchased directly from Vaisala with serial

numbers < E4430001 require approximately 5 seconds warm up

time.

The HMP155A output scale is 0 to 1000 millivolts for the temperature range of

–80 to 60 °C (–112 to 140 °F) and for the relative humidity range of 0 to 100%.

Multipliers and offsets for converting voltage to temperature and relative

humidity are listed in TABLE 7-3 and TABLE 7-4 respectively.

TABLE 7-3. Parameters for Temperature

Units Multiplier

(degrees mV

–1

)

Offset

(degrees)

Celsius 0.14 –80

Fahrenheit 0.252 –112

TABLE 7-4. Parameters for Relative Humidity

Units Multiplier

(% mV

–1

)

Offset

(%)

Percent 0.1 0

Fraction 0.001 0

7.4 Long Lead Lengths

This section describes the error associated with measuring the HMP155A with

a single-ended measurement if the probe has a long cable. To avoid these

problems, Campbell Scientific recommends measuring the HMP155A using a

differential analog measurement (Instruction 2) when long lead lengths are

required. Generic datalogger connections for measuring the HMP155A using a

differential measurement are given in TABLE 7-2.

Understanding the details in this section is not required for the general

operation of the HMP155A with Campbell Scientific’s dataloggers.

NOTE

1 2 ... 16 17 18 19 20 21 22 23 24 25 26 ... 43 44

Commentaires sur ces manuels

Pas de commentaire

Campbell HMP 35A Manuel d'instructions Page 21

Commentaires sur ces manuels

Produits connexes et manuels pour Mesure, test et contrôle Campbell HMP 35A