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CS106 Barometric Pressure Sensor

8. Operations

8.1 Multiplier and Offset Calculation

The multiplier and offset in the VoltSE() CRBasic instruction convert

millivolts to millibar or hPa. The output from the sensor is 0 to 2.5 V or 0 to

2500 mV and the sensor’s operating range is from 500 to 1100 mbars (hPa).

Equation 1 uses these values to calculate the multiplier:

Multiplier m =

1100−500

2500−0

600

2500

= 0.24 (1)

The offset is the barometric value at sea level (see Eq 2).

Offset: o= 500 (mbar or hPa )

The final result according to FIGURE 8-1 is:

y = 0.24





+ 500 mbar (2)

FIGURE 8-1. Point slope graph

8.2 Conversion Factors

In the example program, 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 the CRBasic

program. See TABLE 8-1 below for conversion factors.

TABLE 8-1. Conversion Factors for

Alternative Pressure Units

To Find

Multiply by

hPa or mb 1.0

kPa 0.1

mm of Hg 0.75006

in of Hg 0.02953

Psi 0.0145

Atm 0.00099

Torr 0.75006

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Campbell CS106 Manuale delle Istruzioni Pagina 19