Work out analogue sensor scaling instantly with clear inputs, formula shown and shareable results.
Scaling a 4-20 mA transmitter is a linear map: fraction of span equals (reading - 4)/16, and the engineering value is the minimum plus that fraction of the range. The live-zero at 4 mA is deliberate — a broken wire reads 0 mA, which is distinguishable from a genuine zero measurement.
Linear scaling
value = min + (reading - signal min) / (signal max - signal min) x (max - min)
The 4 mA live zero powers the transmitter and lets a broken loop be detected, since 0 mA can never be a valid reading.
Current is unaffected by wiring resistance, so long cable runs cause no error, and the loop is far less susceptible to induced noise.