Single-Precision Real/Double-Precision Real Data - Mitsubishi Electric MELSEC Q Series Structured Programming Manual

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4.4.4

Single-precision real/double-precision real data

Single-precision real/double-precision real data are 32-bit floating-point data used in basic
instructions and application instructions.
Real number data can be stored only in word devices.
For FXCPU, double-precision real data is not supported.
(1) Single-precision real (single-precision floating-point data)
Devices used in lower 16 bits are specified for instructions that use real number data.
Real number data are stored in 32 bits of 'specified device number' and 'specified device number +1'.
M0
Var_R100
Two points (32 bits) of R100 and R101 are the target word devices
Remark
b31
b31
Sign
b23 to b30
(2) Double-precision real (double-precision floating-point data)
Devices used in lower 16 bits are specified for instructions that use real number data.
Real number data are stored in 64 bits of 'specified device number' and 'specified device
number + 3'.
Transfers real number data
EMOV
EN
ENO
s
d
Var_D0
Floating-point data are represented by two word devices.
[Exponent]
[Sign] 1. [Fraction] 2
The following explains the bit configuration and its meaning when floating-point
data are internally represented.
b30
to
b23
b22
b23 to b30
Exponent
• Sign
b31 represents a sign.
0: Positive
1: Negative
• Exponent
b23 to b30 represent n of 2
The values of n are as follows according to BIN values of b23 to b30.
FF
FE
FD
H
H
H
n
126
Not used 127
• Fraction
23 bits of b0 to b22 represent a value of XXXXXX... when the fraction is
expressed as 1.XXXXXX... in binary.
4.4.4 Single-precision real/double-precision real data
Two points (32 bits) of D0 and D1
are the target word devices
to
b16
b15
b0 to b22
Fraction
n
.
81
80
7F
7E
H
H
H
H
2
1
0
-1
4.4 Method for Specifying Data
4
to
b0
02
01
00
H
H
H
-125 -126 Not used
4-29

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