Using Real Number Data - Mitsubishi MELSEC Q Series Programming Manual

(2) Using word devices
A word device designates devices used by the lower 16 bits of data. A 32-bit instruction
uses (designation device number) and (designation device number + 1).
3.2.4

Using real number data

Real number data is floating decimal point data used with basic instructions and application
instructions.
Only word devices are capable of storing real number data.
(1) Single-precision floating-point data
Instructions which deal with single-precision floating-point data designate devices which are
used for the lower 16 bits of data.
Single-precision floating-point data are stored in the 32 bits which make up (designated
device number) and (designated device number + 1).
3-8
M0
DMOV K100
M0
EMOV R100
Remark
In sequence programs, floating decimal point data are designated by E
Single-precision floating-point data uses two word devices and is expressed in
the following manner:
[Sign] 1. [Mantissa part]
The bit configuration and meaning of the internal representation of single-
precision floating-point data is as follows:
b31 b30
to
b31 b23 to b30
Exponent part
Sign
• Sign The sign is represented at b31.
0: Positive
1: Negative
• Exponent part The n of 2n is represented from b23 to b30.
Depending on the BIN value of b23 to b30, the value of n is as follows:
FF
b23 to b30 H
Not used 127
n
D0
Designation of 2 points of
word devices D0 and D1 (32 bits)
32-bit data transfer instruction
D0
Designation of 2 points of word devices D0 and D1
(32 bits)
Designation of 2 points of R100 and R101 (32 bits)
Single-precision floating-point data transfer instruction
[Exponent part]
2
b23 b22 b16
to
FE FD
H H 81
126
2
b15
to
b0 to b22
Mantissa part
80 7F H 7E H
1 0 -1
.
b0
02 01 00
-125 -126 Not used