Campbell CS106 Instrukcja Obsługi Pobierz pdf (Strona 13)

CS106 Barometric Pressure Sensor

4. Programming

The CS106 sensor is measured using the singled-ended voltage measurement

instruction (VoltSe in CRBasic or P1 in Edlog).

Atmospheric pressure changes little with time. In most weather station

applications measuring pressure once an hour is adequate.

Program Example 1 is for the dataloggers that use the CRBasic language, such

as CR200(X), CR800, CR850, CR1000, CR3000, CR5000, and CR9000(X).

In the example, the CR1000 measures the CS106 once an hour in a program

that runs at 1 Hz. In order to keep the CR1000 running in a pipeline mode, the

measurement instruction is placed outside the “If” statement. The

measurement is made every scan, and the measured value is first written into a

temporary variable called "CS106_temp". Once the CS106 is turned on one

minute before the hour, the CS106 starts to make the correct pressure

measurements. At the top of the hour, the correct value is copied into the

current variable called "pressure", and the sensor is turned off immediately.

In Program Example 1, the integration parameter for the VoltSe instruction is

_60Hz. However, for Eddy Covariance programs or other datalogger

programs that are executed at a higher frequency, the integration parameter

should be 250 µsec instead of _60Hz or _50Hz. This prevents skipped scans.

In Program Example 2, the CR10X datalogger (Edlog datalogger) turns on the

CS106 one minute before the top of the hour using a control port. On the hour

the datalogger measures the CS106, and then it turns the CS106 off.

4.1 Conversion Factors

In the example programs, the pressure is reported in millibars (mb). To report

pressure in different units, multiply the measured pressure by the appropriate

conversion factor. This is done by including an expression in a CRBasic

program or using Instruction 37 (P37) in an Edlog program. See Table 4-1

below for conversion factors.

TABLE 4-1. Conversion Factors for

Alternative Pressure Units

To Find Multiply by

hPa 1.0

kPa 0.1

mm of Hg 0.75006

in of Hg 0.02953

Psi 0.0145

Atm 0.00099

Torr 0.75006

1 2 ... 8 9 10 11 12 13 14 15 16 17 18 19 20

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Campbell CS106 Instrukcja Obsługi Strona 13