Scale an analog input 4-20 mA -30° +60° on a AM2 module

Yves-M

Thank you verry much.

why must this be done in two steps ?

Can it also wit one dec behind ?

With a 4-20 mA you can only use 800 of the 1000 units that the A/D converter provides.
Your temperature range is -30 - 60 °C, i.e. a difference of 90 °C.
800 * X = 90
From this follows: 90/800 = X = 0.1125
In order to generate the range of 90 from the 800 units, the 800 units must be multiplied by 0.1125.
With the analog amplifier, however, only 2 decimal places can be specified. That would mean you could only enter 0.11 or 0.12. This would falsify the value.
Therefore 2 amplifiers.
The first amplfies with 1.25, so the 800 usable units then become 1000.
The second amplifies with 0.09 so 1000 units then become 90.
1.25 * 0.09 = 0.1125. 

If you want a decimal place, then must you set the GAIN in the second amplifier from 0.09 to 0.9. The Min to -300, the Max to 600 and the OFFSET to -300