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5.0 Calibration Notes
There is a time averaging (dampen) function that is set in the FX-300-ISE at the factory. This value
is configurable for both the extent of time averaging for the measure and calibrate modes separately.
If you find that you wish to have more or less time averaging than what is provided on your unit at
present, contact the factory for assistance with this. These values cannot be modified in the field but
rather need to be changed at the factory. The preset values are fine for the vast majority of users and
applications although they can be modified upon request without incurring any cost.
The slope parameter will only be changed when a 2-point slope calibration is performed. After
calibration the slope should be at or very close to the default value. If not this indicates the calibration
was not performed properly. Parameter P 15 allows you to both view and manually modify the
working slope.
You can view the sensor slope resulting from a 2-point calibration with parameter P15 and the sensor
offset resulting from a 2-point calibration with parameter P14. If you perform a 1-point grab sample
offset subsequently the offset (P14) will change whereas the sensor slope (P15) will remain from your
2-point slope calibration.
All settings are stored in EEPROM so the unit can be powered down without loss of configuration or
calibration. The ‘hold’ feature is automatically activated each time any 2-point or 1-point calibration is
performed. This means that the last process value will continue to be sent via the analog 4-20mA and
Modbus digital output before entering the calibration mode. This is the default behavior and can only
be modified at the Foxcroft factory if this is not desired.
The decimal place on the display will automatically move as appropriate based upon the ppm value
of the sensor reading. Note that the display will always auto-range from 0.00 to 9.99, 00.0 to 99.9
and 000 to 999 ppm. Your analog and digital Modbus output will, however, be defined as selected
in parameter P09. This means that your output may be maxed out and not reflect the exact process
reading if you selected too low a range for your output scaling in P09.
5 Calibration
