**Siemens PLC Analog Input Scaling**

The following variables are pertinent to the scaling formula:

Ov = scaled output value

Iv = analog input value

Osh = high limit of the scale for the scaled output value

Osl = low limit of the scale for the scaled output value

Ish = high limit of the scale for the analog input value

Isl = low limit of the scale for the analog input value

The scaling scheme can be diagrammed as follows:

The following formula for calculating the scaled value can be derived from the diagram:

Ov = [(Osh – Osl) * (Iv -Isl) / (Ish – Isl)] + Osl

Which can be rewritten as:

Ov = [(Osh -Osl)/(lsh-lsl)/(lsh -lsl)] + Osl