Справочник Пользователя для Mitsubishi Electronics QnUCPU
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Appendix 3.4 Functions
Appendix 3.4.1 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 selecting the item shown below (default: selected).
instructions. Note, however, that internal operation processing can be performed in double precision
by selecting the item shown below (default: selected).
(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. There-
fore, the "Perform internal arithmetic operations in double precision" item in the PLC system tab of the PLC
parameter dialog box cannot be selected.
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 selected 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, replace-
ment 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 prob-
lems in the system.
The operation can be performed either in single precision or double precision depending on the data. There-
fore, the "Perform internal arithmetic operations in double precision" item in the PLC system tab of the PLC
parameter dialog box cannot be selected.
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 selected 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, replace-
ment 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 prob-
lems in the system.
Figure App.19 PLC system tab
Selected by default.