Campbell Scientific CS106 Barometer - Manual (Page 19)

CS106 Barometric Pressure Sensor
Volt (SE) (P1)
1: 1 Reps
2: 25 2500 mV 60 Hz Rejection Range
3: 1 SE Channel
4: 1 Loc [ CS106 ]
5: 0.240 Multiplier
6: 500 Offset
At sea level, a multiplier of 0.24 and an offset of 500 will report the barometric
pressure in mbar or hPa. The offset will need to be adjusted if the barometer is
not at sea level (see Section 8.5, Correcting Pressure to Sea Level). If different
barometric pressure units are desired, see Section 8.2, Conversion Factors.
Often, the If time is (P92) Edlog instruction is used to only power the
barometer while making the measurements. Atmospheric pressure changes
little with time. In most weather station applications, measuring the barometer
pressure once an hour is adequate. See Appendix B, Example Programs, for
more information.
8. Operation
8.1 Multiplier and Offset Calculation
The multiplier and offset in the VoltSE() CRBasic or Volt (SE) (P1) Edlog
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
= 0.25 (1)
The offset is the barometric value at sea level (see Equation 2).
Offset: o = 500 (mbar or hPa )
The final result according to FIGURE 8-1 is:
y = 0.24 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚
𝑚𝑚𝑚𝑚
+ 500 mbar (2)
FIGURE 8-1. Point slope graph
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