Campbell CR800 Series, Operator'S Manual

Page: 214 / 598

Section 7. Installation
214
PortSet (4,ToggleLED) 'Set control port according
'to result of processing
NextScan
EndProg
7.7.11 Field Calibration — Details
Related Topics:
• Field Calibration — Overview
(p. 75)
•
Field Calibration — Details
(p. 214)
Calibration increases accuracy of a sensor by adjusting or correcting its output to
match independently verified quantities. Adjusting a sensor output signal is
preferred, but not always possible or practical. By using the FieldCal() or
FieldCalStrain() instruction, a linear sensor output can be corrected in the CR800
after the measurement by adjusting the multiplier and offset.
When included in the CRBasic program, FieldCal() and FieldCalStrain() can be
used through a datalogger support software calibration wizard
(p. 491).
Help for
using the wizard is available in the software.
A more arcane procedure that does not require a PC can be executed though the
CR1000KD Keyboard / Displayor. If you do not have a keyboard, the same
procedure can be done in a numeric monitor
(p. 506).
Numeric monitor screen
captures are used in the following procedures. Running through these procedures
will give you a foundation for how field calibration works, but use of the
calibration wizard for routine work is recommended.
More detail is available in CRBasic Editor Help .
7.7.11.1 Field Calibration CAL Files
Calibration data are stored automatically, usually on the CR800 CPU: drive, in
CAL (.cal) files. These data become the source for calibration factors when
requested by the LoadFieldCal() instruction. A file is created automatically on
the same CR800 memory drive and given the same name as the program that
creates and uses it. For example, the CRBasic program file CPU:MyProg.cr8
generates the CAL file CPU:MyProg.cal.
CAL files are created if a program using FieldCal() or FieldCalStrain() does not
find an existing, compatible CAL file. Files are updated with each successful
calibration with new calibration factors factors. A calibration history is recorded
only if the CRBasic program creates a
data table
(p. 495)
with the
SampleFieldCal()
instruction.
Note CAL files created by FieldCal() and FieldCalStrain() differ from
files created by the
CalFile()
instruction See File Management in CR800
Memory
(p. 416).