Mitsubishi Electric MELSEC Q Series Programming Manual page 45

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'.
M0
EDMOV
EN ENO
d
Var_R100
Four points (64 bits) of R100, R101, R102, and R103 are the target word devices
Floating-point data are represented by four word devices.
[Exponent]
[Sign] 1. [Fraction]  2
The following explains the bit configuration and its meaning when floating-point data are internally represented.
b63 b62 b52 b51
to
b63
b52 to b62
Exponent
Sign
• Sign: The most significant bit, b63, is the sign bit.
• 0: Positive
• 1: Negative
• Exponent: The 11 bits, b52 to b62, represent the excess n of 2
b52 to b62.
b52 to b62 7FF 7FE 7FD
H H
n Not used 1023 1022
• Mantissa: Each of the 52 bits, b0 to b51, represents the "XXXXXX..." portion when the data is represented in binary,
"1.XXXXXX...".
Transfers real number data
Var_D0 Four points (64 bits) of D0, D1, D2, and D3
are the target word devices
b16 b15
to
b0 to b51
Fraction
400 3FF 3FE
H H H H
1 0 -1
to
n
. The values of n are as follows according to BIN values of
3FD 3FC 02
H H H
-2 -3 -1021 -1022 Not used
b0
01 00
H H
4 PROGRAM CONFIGURATION
4.4 Method for Specifying Data
4
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