Mitsubishi Electric melsec q00ujcpu User Manual page 586

(3) Advantages and disadvantages when using the double-precision floating-point data of
the Universal model QCPU
TableApp.32 shows the advantages and disadvantages when executing the double-precision floating-point opera-
tion instructions in the Universal model QCPU.
If higher accuracy is required in floating-point operations, it is recommended to replace the instruc-
tions with the double-precision floating-point operation instructions.
TableApp.34 Advantages and disadvantages when using the double-precision floating-point operation instructions
The results are more accurate than those of the
single-precision floating-point operation
instructions.
*1: The processing speed of the double-precision floating-point operation instructions in the Universal model QCPU is higher
than that of floating-point operation instructions using internal double-precision operations in the High Performance
model QCPU.
TableApp.33 shows the comparison between single-precision and double precision floating-point data.
TableApp.35 Comparison between single-precision and double precision floating-point data
Item
Word point required for data retention
Setting range
Mantissa
Precision (number of bits) Exponent
Sign
Data comparison (Conductive
status) (LDE>= / LDED>=)
Data transfer
Instruction processing
(EMOV/EDMOV)
speed (Q04UDHCPU/
Q06UDHCPU) (Maximum)
Addition (3 devices)
(E+ / ED+)
SIN operation (SIN/SIND)
Advantage
Single-precision floating-point
Disadvantage
The instruction processing speed is slower than that of the single-
precision floating-point operation instructions.
Double-precision floating-operation data use twice as many word device
points as single-precision floating-operation data.
data
2 words
128 -126
-2 <N -2 , 0,
-126 128
2 N<2
23
bits
8
bits
1
bits
5.5
µs
0.019
µs
0.0665
µs
5.7
µs
APPENDICES
*1
Double-precision floating-point
data
4 words
1024 -1022
-2 <N -2 , 0,
-1022 1024
2 N<2
52
bits
11
bits
1
bits
9.0
µs
5.0
µs
9.2
µs
13.8
µs
App - 42
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