Instrument Span and Offset

span and offset and equating error with offset is not entirely implausible. I will assume that is what is going on.

The idea is based on the linear transform


Where C is the offset and M the span.

I normally proceed as follows

  1. Inject a zero signal
  2. Adjust offset for zero indicated
  3. Inject a full-scale signal
  4. Adjust span for full scale indicated

Repeat the above at least 3 times, until within expected tolerance.

Sometimes you can’t inject exactly zero and 100%, but you will need two points as widely saved as possible. And some arithmetic.

Credits: Robert

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