Campbell Scientific CR6 CR6 Measurement and Control System - Page 223

Section 7. Installation Scan(100,mSec,0,0) 'SIMULATE SIGNAL THEN MAKE THE MEASUREMENT 'Multiplier calibration is applied when variable CalMode = 6 ExciteV(U11,SimulatedWaterContentSignal,0) VoltSE(WC,1,mV5000,U1,1,0,15000,WCMultiplier,0) 'PERFORM A MULTIPLIER CALIBRATION. 'Start by setting variable CalMode = 1. Finished when variable CalMode = 6. 'FieldCal(Function, MeasureVar, Reps, MultVar, OffsetVar, Mode, KnownVar, Index, Avg) FieldCal(3,WC,1,WCMultiplier,0,CalMode,KnownWC,1,30) 'If there was a calibration, store it into data table CalHist CallTable(CalHist) NextScan EndProg 7.9.12.5.5 Zero Basis (Option 4) Zero basis point calibration loads values into zero-point variables to track conditions at the time of the zero calibration. The syntax is: FieldCal (4,Accel,1,0,ZeroState,Mode,0,1,Avg) When a calibration is performed, the current Accel value is loaded into ZeroState. Uses for a zero-basis point calibration include applications wherein the result is based not only on the zero offset for a single sensor, but the zero state of multiple sensors. For example, a non-vented piezometer whose result should take into account a zero reading from the sensor as well as the effects due to temperature and barometric pressure changes with respect to their values at the time of calibration. Such an equation might look like: Press = G(R0 - R1) + K(T0 - T1) + (S0 - S1) Where, Press = current result in the correct engineering units G = the sensors gage factor R0 = the sensor output at the zero state (out of water) R1 = current output from the sensor K = the sensors temperature correction coefficient T0 = The recorded temperature at the time of the zero state T1 = current temperature measurement result S0 = The recorded barometric pressure at the time of the zero state S1 = The current barometric measurement result 223