Campbell Scientific CR6 CR6 Measurement and Control System - Page 210

Field Calibration - Details

Page 210 highlights

Section 7. Installation the file, as discussed previously, and processing the file using CardConvert software. Q: What happens when a card is inserted? A: When a card is inserted, whether it is a new card or the previously used card, a new file is always created. Q: What does a power cycle or program restart do? A: Each time the program starts, whether by user control, power cycle, or a watchdog, TableFile() with Option 64 will create a new file. Q: What happens when a card is filled? A: If the memory card fills, new data are written over oldest data. A card must be exchanged before it fills, or the oldest data will be overwritten by incoming new records and lost. During the card exchange, once the old card is removed, the new card must be inserted before the data table in datalogger CPU memory rings2, or data will be overwritten and lost. For example, consider an application wherein the data table in datalogger CPU memory has a capacity for about 45 minutes of data3. The exchange must take place anytime before the 45 minutes expire. If the exchange is delayed by an additional 5 minutes, 5 minutes of data at the beginning of the last 45 minute interval (since it is the oldest data) will be overwritten in CPU memory before transfer to the new card and lost. 1 Other options of TableFile() do not pre-allocate memory, so they should be avoided when collecting high-frequency time-series data. More information is available in CRBasic Editor Help. 2 "rings": the datalogger has a ring memory. In other words, once filled, rather than stopping when full, oldest data are overwritten by new data. In this context, "rings" designates when new data begins to overwrite the oldest data. 3 CPU data table fill times can be confirmed in the datalogger Status table. 7.9.12 Field Calibration - Details Reading List: • Field Calibration - Overview (p. 70) • Field Calibration - Details (p. 210) 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 CR6 after the measurement by adjusting the multiplier and offset. When included in the CR6 CRBasic program, FieldCal() and FieldCalStrain() can be used through a datalogger support software (p. 89) calibration wizard (p. 490). Help for using the wizard is available in the software. A more arcane procedure can be executed though the CR1000KD Keyboard / Display or datalogger support software numeric monitor. The numeric monitor procedure is used in the examples below to demonstrate the workings of the calibration functions. Syntax of FieldCal() and FieldCalStrain() is summarized in the section Calibration Functions (p. 575). More detail is available in CRBasic Editor Help. 210

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Section 7.
Installation
the file, as discussed previously, and processing the file using
CardConvert
software.
Q:
What happens when a card is inserted?
A:
When a card is inserted, whether it is a new card or the previously used card, a
new file is always created.
Q:
What does a power cycle or program restart do?
A:
Each time the program starts, whether by user control, power cycle, or a
watchdog,
TableFile()
with
Option 64
will create a new file.
Q:
What happens when a card is filled?
A:
If the memory card fills, new data are written over oldest data.
A card must be
exchanged before it fills, or the oldest data will be overwritten by incoming new
records and lost.
During the card exchange, once the old card is removed, the new
card must be inserted before the data table in datalogger CPU memory rings
2
, or
data will be overwritten and lost.
For example, consider an application wherein
the data table in datalogger CPU memory has a capacity for about 45 minutes of
data
3
.
The exchange must take place anytime before the 45 minutes expire.
If the
exchange is delayed by an additional 5 minutes, 5 minutes of data at the beginning
of the last 45 minute interval (since it is the oldest data) will be overwritten in
CPU memory before transfer to the new card and lost.
1
Other options of
TableFile()
do not pre-allocate memory, so they should be avoided when collecting
high-frequency time-series data.
More information is available in
CRBasic Editor Help
.
2
"rings": the datalogger has a ring memory.
In other words, once filled, rather than stopping when
full, oldest data are overwritten by new data.
In this context, "rings" designates when new data begins
to overwrite the oldest data.
3
CPU data table fill times can be confirmed in the datalogger
Status
table.
7.9.12 Field Calibration — Details
Reading List:
Field Calibration — Overview
(p. 70)
Field Calibration — Details
(p. 210)
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 CR6
after the measurement by adjusting the multiplier and offset.
When included in the CR6 CRBasic program,
FieldCal()
and
FieldCalStrain()
can be used through a
datalogger support software
(p. 89)
calibration wizard
(p. 490).
Help for using the wizard is available in the software.
A more arcane procedure
can be executed though the CR1000KD Keyboard / Display or datalogger support
software numeric monitor.
The numeric monitor procedure is used in the
examples below to demonstrate the workings of the calibration functions.
Syntax of
FieldCal()
and
FieldCalStrain()
is summarized in the section
Calibration Functions
(p. 575).
More detail is available in
CRBasic Editor Help
.
210