Appendix B: Worksheets; Calibrating The Bar Graph To Higher Or Lower Range - Global Water GL400 User Manual

Appendix B

Appendix B: Worksheets

Calibrating the Bar Graph to Higher or Lower Range

With some sensors it is either impractical or unfeasible to reach the full-scale or lower scale of its range.
This will not affect the actual reading of the datalogger but it will cause the bar graph to work incorrectly.
Here are the equations for finding new limits on the bar graph. First take the two coordinates that were
found during calibration*.
(High EU __________, High Raw __________) and
(Low EU __________, Low Raw __________).
Now calculate the slope using this equation:
m = (High Raw – Low Raw) / (High EU – Low EU)
m = ___________
Next find the y-intercept:
b = High Raw - (m * High EU)
b = ___________
Now you can calculate the new "Raw" value for any Engineering Unit.
New Raw = (m * New EU) + b
New Raw = ___________
Finally, enter these new "Raw" values into your datalogger and verify the readings are correct*.
*See Analog Channel Calibration, pages 25 – 27
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