Campbell Scientific CR800 and CR850 Measurement and Control Systems - Manual (Page 153)

Section 7. Installation
153
topics. The most comprehensive resource to date covering use of FieldCal() and
FieldCalStrain() is RTDAQ software documentation. Be aware that,
• the CR800 does not check for out-of-bounds values in mode variables.
• valid mode variable entries are "1" or "4".
7.8.1.4.1 Single-Point Calibrations (zero, offset, or zero basis)
Use this single-point calibration procedure to adjust an offset (y-intercept). See
Zero (Option 0)
(p. 156)
and Offset (Option 1)
(p. 156)
for demonstration programs:
1. Use a separate FieldCal() instruction and separate field cal variables for each
sensor to be calibrated. In the CRBasic program , put the FieldCal()
instruction immediately below the associated measurement instruction.
2. Set mode variable = 0 or 6 before starting.
3. Place the sensor into zeroing or offset condition.
4. Set KnownVar variable to the offset or zero value.
5. Set mode variable = 1 to start calibration.
Mode Variable Interpretation
> 0 and ≠ 6 calibration in progress
< 0 calibration encountered an error
2 calibration in process
6 calibration complete.
7.8.1.4.2 Two-point Calibrations (multiplier / gain)
Use this two-point calibration procedure to adjust multipliers (slopes) and offsets
(y-intercepts). See Two Point Slope and Offset (Option 2)
(p. 159)
and Two Point
Slope Only (Option 3)
(p. 161)
for demonstration programs:
1. Use a separate FieldCal() instruction and separate, related variables for each
sensor to be calibrated.
2. Ensure mode variable = 0 or 6 before starting.
a. If Mode > 0 and ≠ 6, calibration is in progress.
b. If Mode < 0, calibration encountered an error.
3. Place sensor into first known point condition.
4. Set KnownVar variable to first known point.
5. Set Mode variable = 1 to start first part of calibration.
a. Mode = 2 (automatic) during the first point calibration.
b. Mode = 3 (automatic) when the first point is completed.
6. Place sensor into second known point condition.
7. Set KnownVar variable to second known point.