Campbell Scientific CS431 Submersible Pressure Transducer - Manual (Page 13)

CS431 Submersible Pressure Transducer
'Sensor 2 (typical 15 psig sensor)
m2(2)
= 0.000000133861
m1(2) = 0.000001790422
m0(2) = 0.192297242812
b2(2) = 0.000040080304
b1(2) = -0.001486634952
b0(2) = 0.176678958007
Scan(500,mSec,1,0)
'scan once every 500 msec
ExciteV (Vx1,800,0) 'excite voltage of 800 mV
Delay (0,25,mSec)
VoltDiff (V(1),1,mV25,1,false,0,_60Hz,1.0,0) 'Vr 1st sensor, diff ch 1
VoltDiff (V(2),1,mV25,2,true,0,_60Hz,1.0,0) 'Vo 1st sensor, diff ch 2
VoltDiff (V(3),1,mV25,4,false,0,_60Hz,1.0,0) 'Vr 2nd sensor, diff ch 4
VoltDiff (V(4),1,mV25,5,true,0,_60Hz,1.0,0) 'Vo 2nd sensor, diff ch 5
Therm107
(Temp(1),1,5,Vx3,0,_60hz,1.0,0) 'Temp Out 1st sensor, degC se ch 5,
Therm107 (Temp(2),1,6,Vx3,0,_60hz,1.0,0) 'Temp Out 2nd sensor, degC se ch 6
L(1)=100*(V(2)/V(1)) 'L factor for 1st sensor
L(2)=100*(V(4)/V(3)) 'L factor for 2nd sensor
' Apply enhanced calibration values, results in psi
' Sensor 1
me = (m2(1) * Temp(1)^2) + (m1(1) * Temp(1)) + m0(1)
be = (b2(1) * Temp(1)^2) + (b1(1) * Temp(1)) + b0(1)
P(1) = me * L(1) + be 'pressure in psi
' Sensor 2
me = (m2(2) * Temp(2)^2) + (m1(2) * Temp(2)) + m0(2)
be = (b2(2) * Temp(2)^2) + (b1(2) * Temp(2)) + b0(2)
P(2) = me * L(2) + be 'pressure in psi
CallTable
Table1
NextScan
EndProg
5.2 Edlog Instructions
To program for pressure measurement, a Instruction 8 is used to power the
sensor, and measure two output voltages. The results of this measurement are
then mathematically converted to pressure units. This technique automatically
compensates for voltage drops in the cable and minimizes AC noise.
For programming the temperature measurement, the thermistor circuit is
measured with Instruction 11. If desired INW can provide an enhanced
calibration that takes the pressure and temperature measurements and
mathematically corrects the pressure measurement for thermal errors. This
calibration method typically reduces temperature errors by a factor of 10 (see
Section 5.2.1.2).
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