Mitsubishi MELSEC iQ-F FX5 series User Manual

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1 OVERVIEW
1.2 Data Specification Method
Real number data (floating-point data)
Data size and data range
Real number data includes single-precision 32-bit real number data.
Real number data can be stored only in devices other than bit devices or in single-precision real data type labels.
Configuration of single-precision real number data
Single-precision real number data consists of a sign, mantissa, and exponent, and is expressed as shown below.
The following figure shows the bit configuration of the internal expression of single-precision real number data and the
meaning of each part.
■Sign (1 bit)
This bit represents the positive or negative sign of a numerical value. "0" indicates a positive number or 0. "1" Indicates a
negative number.
■Mantissa (23 bits)
A mantissa means XXXXX of 1.XXXXX2
N
representing a single-precision real number in binary.
■Exponent (8 bits)
An exponent means N of 1.XXXXX2
N
representing a single-precision real number in binary. The following table shows the
relationships between the exponent value and N of a single-precision real number.
Precautions
■When setting an input value of single-precision real number from the engineering tool
The number of significant digits is about 7 because the engineering tool processes single precision real number data in 32-bit
single precision.
When the input value of single-precision real number data exceeds 7 digits, the 8th digit is rounded off.
Therefore, if the rounded-off value goes out of the range from -2147483648 to 2147483647, it will not be an intended value.
Ex.
When "2147483647" is set as an input value, it is handled as "2147484000" because 8th digit "6" is rounded off.
Ex.
When "E1.1754943562" is set as an input value, it is handled as "E1.175494" because 8th digit "3" is rounded off.
Data name Data size Value range
Single-precision real number data (single-precision
floating-point data)
Positive
number
32 bits (2 word) 2
-126
 real number<2
128
Zero 0
Negative
number
-2
128
<real number-2
-126
Exponent (b24 to b30) FFH FEH FDH  81H 80H 7FH 7EH  02H 01H 00H
N Not used 127 126  210-1 -125 -126 Not used
1. × 2
MantissaSign
Exponent
b31 b30 ∙∙∙ b23 b22 b16∙∙∙ b15 b0∙∙∙
Sign Exponent Mantissa

Mitsubishi MELSEC iQ-F FX5 series Specifications

General

Brand	Mitsubishi
Model	MELSEC iQ-F FX5 series
Category	Controller
Language	English