I know nothing of GX Works3, but in general built in functions aren't always needed, write your own scaling function:
Code:
// Scaling uses this formula:
// Ov = [(Osh – Osl) * (Iv - Isl) / (Ish – Isl)] + Osl
//
// 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