3 CONFIGURATION OF INSTRUCTIONS
3.6 Cautions on Programming (Operation Errors)
113
3
■Character string data
• For the Basic model QCPU, High Performance model QCPU, Process CPU, and Redundant CPU.
Because all character string data is of variable length, device range checks are performed.
When the device number is outside the device range, an operation error occurs.
For example, in a case where the data register has been allocated 12K points, there will be an error if it exceeds D12287.
The device range check is performed even when the index modification is specified.
In case that the index modification is specified, if the start device number exceeds the device range, an error does not occur.
Another device is accessed.
• For the Universal model QCPU and LCPU
Because all character string data is of variable length, device range checks are performed.
When the device number is outside the device range, an operation error occurs.
For example, in a case where the data register has been allocated 12K points, there will be an error if it exceeds D12287.
The device range check is performed even when the index modification is specified. In case that the index modification is
specified, an error occurs if the start device number exceeds the device range.
With changing the settings of the PLC parameter, the device range is not checked.
*1
*1 For the method that the device range check is disabled when the index modification is specified, refer to the User's Manual (Function
Explanation, Program Fundamentals) for the CPU module used.
■Direct access output (DY)
Device range checks are conducted when indexing is performed by direct access output (DY).
$MOV
"ABC"
D12287
This designates D12287 and D12288 as the
target devices for executing the $MOV instruction.
However, since D12288 does not exist,
an operation error occurs.
$MOV
"ABC"
D12287
This designates D12287 and D12288 as the
target devices for executing the $MOV instruction.
However, since D12288 does not exist,
an operation error occurs.
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