In-Situ RDO PRO-X Process Optical Dissolved Oxygen Sensor Manual - Manual (Page 26)

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10. Write the Calibration Update command (0xE001) to the sensor command register.
The sensor will calculate a new slope and offset, write the current time to the last
user calibration time register, and set the next user calibration time register to zero
(disabled). If the concentrations at 100% and 0% saturation are equal, the probe will
return an exception response with code 0x97 (invalid calibration) and not attempt to
compute a new slope and offset due to possible division by zero. If the slope does
not calculate between 0.85 and 1.20 inclusive, or if the offset does not calculate
between -0.2 and +0.2 inclusive, then the probe will return an exception response
with code 0x97 (invalid calibration).The slope and offset will be available for read
but will not be committed to flash.
11. Optional: Read the last user calibration time register, add the next calibration
interval, and write the result to the next user calibration time register.
12. Write the Calibration Mode Off command (0xE002) to the sensor command register
to place the sensor in normal operation. If the calibration mode is turned off without
a calibration update command, or the calibration command returned an exception,
the previous calibration shall be restored.
13. Optional: If you saved the temperature and saturation parameter units at the start of
the process, write the original values back.
14. Optional: If you saved the Sensor Data Cache Timeout register 9463 at the start of
the process, write the original value back.
Calibration Calculations