S7 Analog Scaling Calculator
RAW 0…27648 ↔ ENGINEERING UNITS ENGINEERING VALUE
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REVERSE: ENG. VALUE → RAW
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How it is calculated
Siemens S7 analog inputs map the nominal signal range (e.g. 4–20 mA) to raw integer 0…27648. Scaling: value = min + (raw / 27648) × (max − min). Values above 27648 are overrange; 32767 means wire break / fault — alarm on it, never scale it.
FAQ
Why 27648 and not 32767?
Siemens reserves the band above the nominal span (27649…32511) for overrange and 32767 for fault signalling, so diagnostics survive inside a 16-bit integer.
What raw value equals 12 mA on a 4–20 mA input?
12 mA is 50 % of span → raw ≈ 13824. Formula: raw = (mA − 4) / 16 × 27648.
Which TIA Portal instructions implement this?
NORM_X (raw → 0.0…1.0) followed by SCALE_X (→ engineering units); the reverse pair drives analog outputs.