APPENDICES
Appendix 5 Method of replacing High Performance model QCPU with Universal model QCPU
App
- 140
9
P
a
ra
met
e
rs
10
Device
Exp
la
n
at
ion
11
CP
U
M
odu
le
P
ro
cessi
ng
Ti
m
e
12
P
roc
e
d
ure
f
or W
rit
in
g
P
rog
ra
m t
o CP
U Mo
du
le
A
p
pe
nd
ic
e
s
In
de
x
Appendix 5.4 FUNCTIONS
Appendix 5.4.1 Floating-point Operation Instructions
(1) Differences between High Performance model QCPU and Universal
model QCPU
(a) High Performance model QCPU
The High Performance model QCPU can perform only the single-precision
floating-point operation instructions. Note, however, that internal operation
processing can be performed in double precision by checking the item on the PLC
system setting tab of PLC parameter as shown below. (Default: Checked)
(b) Universal model QCPU
The Universal model QCPU supports the double-precision floating-point operation
instructions.
The operation can be performed either in single precision or double precision
depending on the data. Therefore, "Perform internal arithmetic operations in
double precision" on the PLC system setting tab of PLC parameter cannot be set
in the Universal model QCPU.
Because of this new function, operation results (both in single precision and
double precision) slightly differ between the High Performance model QCPU and
the Universal model QCPU if "Perform internal arithmetic operations in double
precision" is set in the High Performance model QCPU.
If higher accuracy is required in floating-point operations, replace the floating-
point operation instructions as described in (4). However, if six or less digits are
used as significant digits for the floating-point operation instructions, replacement
is not necessary. The single-precision floating-point operation results in the
Universal model QCPU can be used as they are in the system. When not
replacing instructions, make sure that it does not cause any problems in the actual
system.
Figure App.19 PLC system setting tab
