535
APPENDICES
A
Appendix 5 Replacing Basic Model QCPU or Qn(H)CPU with QnUCPU
Appendix 5.4 Functions
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 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.
Therefore, 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 Page 538, Appendix 5.4.1 (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 the
instructions, ensure that it does not cause any problems in the system.
To Next Page
Loading...
Need help?
General
