Section 7. Installation
Scan
(100,mSec,0,0)
'SIMULATE SIGNAL THEN MAKE THE MEASUREMENT
'Zero calibration is applied when variable CalMode = 6
ExciteV
(Vx1,SimulatedRHSignal,0)
VoltSE
(RH,1,mV2500,1,1,0,250,0.05,RHOffset)
'PERFORM A ZERO CALIBRATION.
'Start by setting variable CalMode = 1. Finished when variable CalMode = 6.
'FieldCal(Function, MeasureVar, Reps, MultVar, OffsetVar, Mode, KnownVar, Index, Avg)
FieldCal
(0,RH,1,0,RHOffset,CalMode,KnownRH,1,30)
'If there was a calibration, store calibration values into data table CalHist
CallTable
(CalHist)
NextScan
EndProg
7.9.12.5.2 FieldCal() Offset (Opt 1) Example
Most CRBasic measurement instructions have a
multiplier
and
offset
parameter.
FieldCal()
Option 1
adjusts the
offset
argument such that the output of the sensor
being calibrated is set to the magnitude of the
FieldCal()
KnownVar
parameter.
Subsequent measurements have the same offset added.
Option 0
does not affect
the
multiplier
argument.
Option 0
does not affect the
multiplier
argument.
Example Case: A sensor measures the salinity of water. Multiplier is known to be
stable, but sensor offset drifts and requires regular offset correction using a
standard solution. The following procedure offsets the measurement to obtain the
calibration report shown.
Table 30.
Calibration Report for Salinity Sensor
CRBasic Variable
At Deployment
At Seven-Day Service
SimulatedSalinitySignal
output
1350
mV
1345
mV
KnownSalintiy
(standard
solution)
30
mg/l
30
mg/l
SalinityMultiplier
0.05
mg/l/mV
0.05
mg/l/mV
SalinityOffset
-37.50
mg/l
-37.23
mg/l
Salinity
reading
30
mg/l
30
mg/l
1. Send CRBasic example
FieldCal() Offset
(p. 217)
to the CR1000. A terminal
configured for excitation has been programmed to simulate a sensor output.
2. To simulate the salinity sensor in a simulated-calibration condition, (in the field
it would be placed in a 30 mg/l standard solution), place a jumper wire
between terminals
VX1
and
SE1
. The following variables are preset by the
program:
SimulatedSalinitySignal
=
1350
,
KnownSalinity
=
30
.
3. To start a simulated calibration, set variable
CalMode
=
1
. When
CalMode
increments to
6
, offset calibration is complete. The calibrated offset will equal
-37.48
mg/l.
4. To continue this example and simulate an offset-drift condition, set variable
SimulatedSalinitySignal
=
1345
.
216
Summary of Contents for CR1000
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Page 456: ...Section 8 Operation Figure 118 Real Time Custom 456 ...
Page 457: ...Section 8 Operation 8 8 1 3 Final Memory Tables Figure 119 Final Memory Tables 457 ...
Page 458: ...Section 8 Operation 8 8 2 Run Stop Program Figure 120 Run Stop Program 458 ...
Page 460: ...Section 8 Operation Figure 122 File Edit 460 ...
Page 461: ...Section 8 Operation 8 8 4 PCCard Memory Card Display Figure 123 PCCard CF Card Display 461 ...
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