How to scale Analog Input values - Siemens PLC


#1

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