Campbell Scientific CR800 and CR850 Measurement and Control Systems - Manual (Page 158)

Section 7. Installation
158
K = temperature correction coefficient (‐0.04 PSI / C° is typical)
T
0
= r temperature at the zero state
T
1
= temperature measurement
S
0
= barometric pressure at the zero state
S
1
= barometric pressure measurement.
The following procedure determines zero offset of the pressure transducer, water
temperature, and barometric pressure readings. Use the external keyboard /
display or support software numeric monitor to change variable values as directed.
Calibration Report for Pressure Transducer
Parameter Measurement
Before Zero Measurement
After Zero
Piezometer Output (digits) 8746 0
Piezometer Temperature (°C) 21.4 0
Barometer Pressure (mb) 991 0
1. Send CRBasic example FieldCal() Zero Basis Demo Program
(p. 158)
to the
CR800.
2. To simulate the pressure transducer in zero conditions:
• Digits_Measured is set to 8746 automatically
• Temp_Measured is set to 21.4 automatically
• BP_Measured to 991
3. To simulate the calibration, change the value in variable CalMode to 1 to start
calibration. When CalMode increments to 6, zero calibrations are complete.
Calibrated offsets will equal 8746 digits, 21.5 C°, and 991 mb.
CRBasic Example 28. FieldCal() Zero Basis Demo Program
'FieldCal zero basis demonstration program
Public Pressure
Public VW(1,6)
Public Equation_Parameters(3)
Alias Equation_Parameters(1) = Digits_Measured
Alias Equation_Parameters(2) = Temp_Measured
Alias Equation_Parameters(3) = BP_Measured