SMA SUNNY CENTRAL - Manual (Page 43)

SMA Solar Technology AG External Sensors
User Manual SC-BEN092751 43
8.2 Calculating Gain and Offset
1. To activate the analog input, you must select a
measurement range for the analog sensor (e.g. +/- 10 V).
2. Name the sensor (e.g. Temperature).
3. Enter the unit of measurement (e.g. W/m²).
4. The displayed value is calculated by means of:
– the value measured by the sensor,
– the value which you have specified as the gain, and
– the value which you have specified as the offset.
5. The gain factor is obtained by dividing the display
range by the measuring range.
6. The offset is calculated by subtracting the product of the gain factor and the lower end of the
measuring range from the lower end of the display range.
Offset = lower end of display range - (gain factor * lower end of measuring range)
Expressed in formulas:
M is a value measured in a range between Ml and Mu.
D is the value displayed in a range between Dl and Du.
Explanation of the Abbreviations Used
Gain: G = (Du - Dl) / (Mu - Ml)
Offset: O = Dl - (G * Ml)
Displayed value: D = (G * M) + O
M measured value Mu upper end of measuring range
Ml lower end of measuring range O offset
G gain D displayed value
Du upper end of display range Dl lower end of display range
[Ain 3 ]
Function AIn 3
...+/- 10V
Name
Radiation
Unit
W/m²
Gain
135
Offset
0
Gain factor =
Display range
Measuring range