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3.6 Cautions on Programming (Operation Errors)
2) Universal model QCPU
The device range is checked.
When the device number is outside the device range, an operation error
occurs.
For example, when12 k points are assigned to a data register, an error occurs
if the device number of the data register exceeds D12287.
The device range is checked even though indexing is executed.
An error occurs when the head device number of the devices with indexing
exceeds the device range.
With changing the settings of the PLC parameter on GX Developer, the device
range is not checked.*
2
*2: For changing the settings of the PLC parameter on GX Developer, refer to the following manual.
• QCPU User's Manual (Function Explanation, Program Fundamentals)
(c) Character string data
Because all character string data is of variable length, device range checks are
performed.
In cases where the corresponding device range has been exceeded, an operation error
will be returned.
For example, in a case where the data register has been allocated 12k points, there will
be an error if it exceeds D12287.
However, with CPUs other than Universal model QCPU, when indexing is executed and
the head device number is outside the device range, no error occurs and the other
devices are accessed.
BMOV D0 K2D12287
When D12287 is specified with the BMOV instruction,
the target devices are D12287 and D12288.
However, an operation error occurs because D12288
does not exist.
D0 D12285Z1
K2
BMOV
D0 D12287Z1 K2BMOV
K2 Z1MOV
When D12287 is specified with the BMOV instruction,
the target devices are D12287 and D12288.
However, an operation error occurs because D12288
does not exist.
An operation error occurs since head device number
is D12289 that exceeds the device range.
$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.