Function makeSignedScaledParam

Signed scaled parameter where wire = domain / factor, using UInt16 as the wire-side schema with two's-complement conversion (Modbus delivers unsigned 16-bit values). Decode validates through the optional domain. Encode fails when value / factor rounds to a word outside -32768..32767. Supply a finite, non-zero factor. The factory does not validate it.

Signed scaled parameter where wire = domain / factor, using UInt16 as the wire-side schema with two's-complement conversion (Modbus delivers unsigned 16-bit values). Decode validates through the optional domain. Encode fails when value / factor rounds to a word outside -32768..32767. Supply a finite, non-zero factor. The factory does not validate it.