Campbell-scientific HMP155A Temperature and Relative Humidity Probe Manuel d'utilisateur télécharger pdf (Page 33)

Appendix B. Example Programs

B.3 Mean Vapor Pressure Examples

These examples compute mean vapor pressure. TABLE B-3 shows the wiring

used for these examples.

TABLE B-3. Wiring for Vapor Pressure Examples

Color Description CR1000 CR10(X)

Yellow Temperature SE 2 (1L) SE 3 (2H)

Blue Relative Humidity SE 1 (1H) SE 4 (2L)

White Signal Reference

Jumper from

SW12V Control

Red Power SW12V SW12 V

Black Power Ground

Clear Shield

B.3.1 CRBasic Vapor Pressure and Saturation Vapor Pressure

Program

Below is an example CR1000 program. Other CRBasic dataloggers are

programmed similarly.

'CR1000 program that calculates Vapor Pressure

Public AirTC

Public RH

Public RH_Frac, e_Sat, e_kPa

DataTable(Temp_RH,True,-1)

DataInterval(0,60,Min,0)

Average(1,AirTC,IEEE4,0)

Sample(1,RH,IEEE4)

Sample(1,e_kPa,IEEE4)

EndTable

BeginProg

Scan(5,Sec,1,0)

'HMP155A Temperature & Relative Humidity Sensor measurements AirTC and RH:

PortSet (9,1)

Delay(0,2,Sec)

VoltSE(AirTC,1,mV2500,2,0,0,_60Hz,.14,-80)

VoltSE(RH,1,mV2500,1,0,0,_60Hz,0.1,0)

PortSet (9,0)

If RH>100 And RH<108 Then RH=100

'Calculate Vapor Pressure

'Convert RH percent to RH Fraction

RH_Frac = RH * 0.01

'Calculate Saturation Vapor Pressure

SatVP(e_Sat, AirTC)

'Compute Vapor Pressure, RH must be a fraction

e_kPa = e_Sat * RH_Frac

CallTable(Temp_RH)

NextScan

EndProg

B-5

1 2 ... 28 29 30 31 32 33 34 35 36 37 38 ... 47 48

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