Mitsubishi MELSEC-Q Series Programming Manual page 50

(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'.
Remark
b52 to b62
4.4 Method for Specifying Data
4-28
4.4.4 Single-precision real/double-precision real data
M0
EDMOV
EN ENO
d
Var_R100
Four points (64 bits) of R100, R101, R102, and R103 are the target word devices
1) Floating-point data are represented by four word devices.
[Sign] 1. [Fraction] 2
The following explains the bit configuration and its meaning when floating-point
data are internally represented.
b63 b62
to
b63
b52 to b62
Exponent
Sign
• Sign
b63 represents a sign.
0: Positive
1: Negative
• Exponent
b52 to b62 represent n of 2
The values of n are as follows according to BIN values of b52 to b62.
7FF 7FE 7FD
H H H
n
Not used 1023 1022
• Fraction
52 bits of b0 to b51 represent a value of XXXXXX... when the fraction is
expressed as 1.XXXXXX... in binary.
Transfers real number data
Var_D0 Four points (64 bits) of D0, D1, D2, and D3
are the target word devices
[Exponent]
b52 b51 b16
to
n
.
400 3FF 3FE
H H H
2 1 0
b15
to
b0 to b51
Fraction
3FD 3FC 02
H H H
-1 -2 -1021 -1022
b0
01 00
H H
Not used