Omron CX-PROGRAMMER V9 - REV 12-2009 Operation Manual page 11

OMRON
WARNING
Caution
Caution
Observe the following precautions when using the PLC Backup Tool.
• Sufficiently check the data that is selected for restoring before performing
the next step. If the correct data is not restored, unexpected operation
may occur in the controlled system after the data is restored.
• Some Special I/O Units and CPU Bus Units operate with parameters that
are stored in the CPU Unit. If one of these Units is selected for backup,
restrictions will be displayed in the Comments Area of the Backup from
PLC Dialog Box. Confirm the restrictions, and always select the Special
I/O Unit or CPU Bus Unit together with the CPU Unit when backing up or
restoring data. If the data from both Units is not backed up or restored
together, unexpected operation may occur in the controlled system.
• If there are any backup restrictions for the Units to which data is being
restored, the restrictions will be displayed in the Comments Area of the
Backup from PLC Dialog Box. Confirm the restrictions, and always take
the required measures. If required measures are not taken, unexpected
operation may occur in the controlled system after the data is restored.
• Forced status can be backed up, but it cannot be restored. If you
restored data that contained forced status, use the CX-Programmer after
restoring the data to force-set or force-reset bits as required. If required
bits are not force-set or force-reset, differences in the forced status in
memory may cause unexpected operation of the controlled system.
• Confirm that stopping PLC operation will not create any problems before
restoring data during PLC operation. If the PLC stops at an unanticipated
time, unexpected operation may occur in the controlled system.
• Always turn the power supply to the PLC OFF and then ON after
restoring data. If the power supply is not turned OFF and then ON,
memory in the PLC may not be updated to the restored data, which may
cause unexpected operation of the controlled system.
Observe the following precaution when specifying a symbol or word
address for an array variable index in a ladder program or when specifying
a symbol for an array variable index in an ST program.
When using a symbol or address to indirectly specify the element number
of an array variable, be sure that the resulting address is not outside the
memory area that contains the first word in the array. For example, use a
symbol comparison instruction or an IF statement to ensure that processing
is performed only when the memory area is not exceeded. If an element
number that exceeds the memory area is specified, data in another
memory area will be read or written, possibly resulting in unexpected
operation.
Observe the following precaution when specifying a symbol or word
address for an offset in a ladder program.
When using a symbol or address to indirectly specify an offset for a
memory address, be sure that the resulting address is not outside the
memory area that contains original address. For example, use a symbol
comparison instruction to ensure that processing is performed only when
the memory area is not exceeded. If the final address (i.e., the original
address plus the specified offset) exceeds the memory area, data in
another memory area will be read or written, possibly resulting in
unexpected operation.
CX-Programmer – Operation Manual
CX-Programmer_Page (
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