Glossary
What is Analogue scaling?
Turning the raw count from an input card into an engineering unit an operator understands: metres, bar or degrees.
The general formula is (raw minus raw low) divided by the raw span, times the engineering span, plus the engineering low. The raw range is vendor-specific: 0…27648 on Siemens, 0…32767 elsewhere.
The result is always clamped with LIMIT so an impossible value never reaches the screen, and the raw range is checked to detect a sensor fault.
Related terms
- Type conversion
- Explicit functions that move a value between types, such as INT_TO_REAL, REAL_TO_INT, TRUNC and TIME_TO_DINT.
- NAMUR NE43
- A recommendation defining current bands outside 4-20 mA that signal a sensor fault rather than a valid measurement.