Siemens 500 NIM - Manual (Page 124)

Floating Point Numbers B-2 SIMATIC TIWAY I Series 500 NIM User Manual
B.1 Introduction
The Series 500 NIM allows IBM r excess 64 and IEEE representation of
floating point data types (noted in Chapter 4).
Floating point formats consist of three parts: the sign bit, the exponent, and
the mantissa, or fraction. For both the IBM and the IEEE formats, the sign
bit indicates the positive or negative value of the mantissa. If the sign bit is
set to one, the floating point number is a negative value. If the bit is set to
zero, the number is positive.
The exponent and fraction of these formats will be described independently
in the following paragraphs.