SGI_PathAdjustValues

[aFouraker]

In the manual linked here for the SGI S20 modules, what is meant by the SGI_PathAdjustValues listed on page 27? 

[cc2go]

The object SGI_PathAdjustValues 0x0298 is read only, it provides for each channel the current stored values of "zero point value", "adjustment factor" and "tare".

[aFouraker]

How should these values be interpretted? How do they effect the read value? Is this a straight linear scaling of the data where the tare value is the y offset and the adjustment factor is the slope? How does the zero-adjustment effect those values?

[cc2go]

not sure if it is like you assume or we're talking from different things. The object is just to see current adjustments.

See chapter 17 Adjustment. The zero-adjustment or better zero-point value, is the zero in your system without load to compensate mechanical or any other effects.

Do you have any special use case in mind (e.g. tension control) or you like to understand in common?

In my point of view the principal settings and effects on the scaling are set in the remanent application objects like “nominal characteristic value” or “nominal load”. The adjustment is the fine tuning to your used sensor and application.

[aFouraker]

What I would like to do is 

a) save the strain gauge reading in its unchanged form, something like a hex value, this will be easier for me to save,

b) understand these settings so that I can transform that hex value into a real value (and vice versa), 

c) save these settings to that I will have a record of the calibration constants over time. In this way, I will be able to tell if a big change occurs between calibrations. 

I will be recording the strain guage readings over a period of a few seconds and storing the data. Instead of storing the float data I would like to store a hex value. The application has historically kept a record of the calibration constants and I would like to continue this and understand how they are related to the unprocessed value.  

Chapter 17 gives a good description of the setup process but not what is happening "under the hood." I want to make use of the features of the strain guage module but also want to understand how these calculated values are used to process the data. 

[cc2go · Accepted solution]

There is no possibility to store a correction curve into the SGI module. It’s just linear.

Is a correction curve with multiple points are needed, than it has to be made in the application.

By reading the values a normalization will be made in the application too.