Example Program - Campbell KH20 Product Manual

Appendix B. Example Program
NOTE
CRBasic Example B-1. CR3000 Program to Measure Water Vapor Fluctuations
'CR3000 Series Data Logger
'This data logger program measures KH20 Krypton Hygrometer.
'The station operator must enter the constant and the calibration value for the KH20.
'Search for the text string "unique" to find the locations of these constants
'and enter the appropriate values found from the calibration sheet of the KH20.
'*** Unit Definitions ***
'Units Description
'ln_mV ln(mV)
'mV millivolts
'rho_w g/m^3
'*** Wiring ***
'ANALOG INPUT
'1H KH20 signal+ (white)
'1L KH20 signal- (black)
'gnd KH20 shield (clear)
'EXTERNAL POWER SUPPLY
'POS KH20 power+ (red)
' data logger POWER IN 12 (red)
'NEG KH20 power- (black)
' KH20 power shield (clear)
' data logger POWER IN G (black)
PipeLineMode
'*** Constants ***
'Measurement Rate
Const SCAN_INTERVAL = 100
'Output period
Const OUTPUT_INTERVAL = 30
Const x = 1
Const kw = -0.150
Const xkw = x*kw
'*** Variables ***
Public panel_temp
Public batt_volt
Public kh(2)
Public rho_w
Alias kh(1) = kh_mV
Alias kh (2) = ln_kh
Units panel_temp = deg_C
Units batt_volt = volts
Units kh_mV = mV
The following example program measures the KH20 at 10Hz, and stores the
average values into a data table called 'stats', as well as the raw data into a data
table called 'ts_data'.
The KH20 does not monitor absolute water vapor concentration.
(natural log of the KH20 millivolts)
'10 Hz
'100 mSec
'Online flux data output interval in minutes.
'Unique path length of the KH20 [cm].
'Unique water vapor absorption coefficient [m^3 / (g cm)].
'Path length times water vapor absorption coefficient [m^3 / g].
B-1