APPENDICES
Appendix 5 Method of replacing High Performance model QCPU with Universal model QCPU
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Appendix 5.4.2 Error Check Processing for Floating-point Data Comparison
Instructions
(1) Input data check
An error check processing for floating-point data comparison instructions performed in
the Universal model QCPU are enhanced. Input of a "special value" (-0, nonnumeric,
unnormalized number, and
) is checked, and if those special values are input, an
OPERATION ERROR (error code: 4140) is detected.
When the LDE , ANDE , ORE , LDED , ANDED , and/or ORED instructions
( indicates one of the followings; =,<>,<,>,<=,>=) are used in the program, an
OPERATION ERROR (error code: 4140) might be detected if invalid floating-point
data exist. This occurs even when interlocks are provided using the valid data flag
(the signal which shows the floating-point validity).
Invalid floating-point data are not stored in the result of operations performed in the
Universal model QCPU. Those invalid data are considered to be stored in the
following cases:
• The same device is used for storing floating-point data and other data, such as
binary values, BCD values, and strings.
Use different devices for storing floating-point data and data other than
floating-point data
• Floating-point data externally written are invalid.
Take measures on the external-source side so that valid data are written.
If an error occurs in the floating-point data comparison instructions, take appropriate
measures to remove error causes described above.
Example 1) Detecting an OPERATION ERROR (error code: 4140) in the LDE
instruction
[Ladder mode] [List mode]
In the ladder block starting from the step 104, the floating-point data comparison
instructions of the step 105 and 109 shall not be executed when the M101 (valid data
flag) is OFF.
However, the LDE<= instruction of the step 105 and the ORE>= instruction of the step
109 are executed regardless of the execution result of the LD instruction of the step
104 in the program above. Therefore, even when the M101 is OFF, an OPERATION
ERROR (error code: 4140) is detected in the LDE<= instruction of the step 105 if a
"special value" is stored in D100.
Method of avoiding an OPERATION ERROR occurrence is described in (2).
