APPENDICES
Appendix 5 Method of replacing High Performance model QCPU with Universal model QCPU
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(3) Advantages and disadvantages when using the double-precision
floating-point data of the Universal model QCPU
TableApp.73 shows the advantages and disadvantages when performing the double-
precision floating-point operation instructions in the Universal model QCPU.
If higher accuracy is required in floating-point operations, it is recommended to
replace the instructions with the double-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.74 shows the comparison between single-precision and double precision
floating-point data.
TableApp.73 Advantages and disadvantages when using the double-precision floating-point
operation instructions
Advantage
Disadvantage
The results are more accurate than those
of the single-precision floating-point
operation instructions.
The instruction processing speed is slower than that of the
single-precision floating-point operation instructions. *1
Double-precision floating-operation data use twice as many
word device points as single-precision floating-operation
data.
TableApp.74 Comparison between single-precision and double precision floating-point data
Item
Single-precision floating-point data Double-precision floating-point data
Word point required for data retention
2 words
4 words
Setting range
-2
128
<N
-2
-126
, 0,
2
-126
N<2
128
-2
1024
<N
-2
-1022
, 0,
2
-1022
N<2
1024
Precision (number of bits)
Mantissa part
23
bits
52
bits
Exponent part
8
bits
11
bits
Sign part
1
bits
1
bits
Instruction processing
speed (Q04UDHCPU/
Q06UDHCPU)(Maximum)
Data comparison
(Conductive status)(LDE>= /
LDED>=)
5.5
µs
9.0
µs
Data transfer(EMOV/
EDMOV)
0.019
µs
5.0
µs
Addition (3 devices)(E+ /
ED+)
0.0665
µs
9.2
µs
SIN operation(SIN/SIND)
5.7
µs
13.8
µs
