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MELSEC-Q
4 SEQUENCE PROGRAM CONFIGURATION AND EXECUTION
CONDITIONS
4.8.4 Real numbers (floating decimal point data)
(1) Real numbers
Real numbers are single precision floating decimal point data.
(2) Internal expression of floating decimal point data
The High Performance model QCPU's internal expression of received real
number data is explained below.
Real number data is expressed as shown below, using 2 word devices.
1. [Mantissa] × 2
(characteristic)
The bit configuration used for internal expression of floating decimal point data is
shown and explained below.
b31 b30 b23 b22 b16 b15 b0
b0 to b22
Mantissa
b23 to b30
Characteristic
b31
Mantissa code
• Mantissa code: The mantissa code is expressed at b31 as follows.
0: Positive
1: Negative
• Characteristic: The "n" of "2n" is expressed in various ways at b23 to b30,
depending on the b23 to b30 BIN value.
b23 to b30
n
FF
H
FE
H
127
FD
H
126
00
H
02
H
-125
01
H
-126
81
H
2
80
H
1
7F
H
0
7E
H
-1
Non-
numeric
Non-
numeric
• Mantissa: For a binary value of 1.XXXXXX..., the "XXXXXX" portion of
the value is expressed at b0 to b22 (23 bits).
(3) Calculation examples
Calculation examples are shown below (the nnnnn "X" indicates an X-system
data expression).
(a) Storing "10"
(10) (1010) (1.01000..... 2 )
10
2
3
2
Mantissa code Positive to 0
Characteristic 3 to 82
H
to (10000010)
2
Mantissa (010 00000 00000 00000 00000)
2
Therefore, the data expression will be 41200000
H
, as shown below.
Code Characteristic Mantissa
0 10000010 01000000000000000000000
412000
00
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