Data Acquisition Idea Exchange

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FlexLogger's 2-point calibration implementation is flawed

Status: New

Basically, FlexLogger limits the range of readings to the values used in the 2 point calibration.  For example, if your sensor has a range of -10 to 10 PSI, and the 2-point cal is done at +/- 10 PSI, FlexLogger will only display values within +/- 10 PSI (and will saturate otherwise).


I totally understand why this is done, but sensors in fact DO read above (and sometimes below) their stated ranges and have documented accuracy (i.e. 1% above 95% full scale) , so clipping the value to the scaling settings in the cal page is the wrong thing to do...the sensor can still be measuring correctly, but FlexLogger will only show the saturated value.


The scaling, however it is done, probably result in a Y=mX + b equation, and FlexLogger should display Y, whatever Y is, regardless of stated sensor range or 2-point cal/scaling.


A worse case is if the sensor has a range of +/- 10 PSI but your cal/verification system is only capable of +/- 5 PSI, you will be limited to +/- 5 PSI with the FlexLogger 2-point cal implementation.


Yes, there are way around this, but why should the user, usually technicians who don't necessarily understand the math or ins/outs of software, have to figure out a way around FlexLogger?