nielsbasjes commented on issue #743:
URL: https://github.com/apache/plc4x/issues/743#issuecomment-1937611549

   Also; I realized a while ago that the only way any library can reliable read 
this device is when this library has a full schema of the device at hand. Only 
by following the constraints imposed by this schema can the library do the 
modbus calls that result in correct data.
   
   Note that the mentioned SunSpec has an even harder schema definition.
   For example this field (they call it point) 
[`A`](https://github.com/sunspec/models/blob/master/json/model_101.json#L31) 
(AC Current) has a scaling factor field 
[`A_SF`](https://github.com/sunspec/models/blob/master/json/model_101.json#L66) 
which means that the value from the registers related to `A` must be multiplied 
by 10^`the value of the field A_SF` to get the actual value.
   
   So to get the value of the field `A` you must read the registers related to 
`A` and `A_SF` before you can determine the actual value.
   
   I have been experimenting for a few months now on how to get to a form of 
schema definition that allows for all of these variants. I'm still working on 
that.
   
   So please just treat this as an FYI around the fact that some devices show 
unexpected behavior if you try to read valid registers in a way that does not 
meet their schema.
   
   
   
   
   


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