Omron CJ2 CPU UNIT SOFTWARE User Manual page 34

• When creating an AUTOEXEC.IOM file from a Programming Device (a Programming Console or
the CX-Programmer) to automatically transfer data at startup, set the first write address to
D20000 and be sure that the size of data written does not exceed the size of the DM Area. When
the data file is read from the Memory Card at startup, data will be written in the CPU Unit starting
at D20000 even if another address was set when the AUTOEXEC.IOM file was created. Also, if
the DM Area is exceeded (which is possible when the CX-Programmer is used), the remaining
data will be written to the EM Area.
• The user program and parameter area data in the CJ2 CPU Units are backed up in the built-in
flash memory. The BKUP indicator will light on the front of the CPU Unit when the backup opera-
tion is in progress. Do not turn OFF the power supply to the CPU Unit when the BKUP indicator is
lit. The data will not be backed up if power is turned OFF.
• Check the user program and Unit parameter settings for proper execution before actually running
them on the Unit. Not checking the program and parameter settings may result in an unexpected
operation.
• When setting a Special I/O Unit or CPU Bus Unit in the I/O tables, carefully check the safety of the
devices at the connection target before restarting the Unit.
• Do not turn OFF the power supply to the PLC when reading or writing a Memory Card. Also, do
not remove the Memory Card when the BUSY indicator is lit. Doing so may make the Memory
Card unusable.
To remove a Memory Card, first press the memory card power supply switch and then wait for the
BUSY indicator to go out before removing the Memory Card.
• When restoring data, carefully check that the selected data is the correct data to be restored
before executing the restore operation. Depending on the contents of the selected data, the con-
trol system may operate unexpectedly after the data is restored.
• Some Special I/O Units and CPU Bus Units operate with parameters stored in the CPU Unit (e.g.,
words allocated in DM Area, data link tables, or Ethernet settings). Information on restrictions will
be displayed in the Information Area in the PLC Backup Tool if there are any restrictions for the
selected CPU Bus Unit or Special I/O Unit. Check the restrictions, and then be sure to select both
the CPU Unit and the CPU Bus Unit or Special I/O Unit when backing up or restoring data. The
control system may operate unexpectedly if the equipment is started with the data backed up or
restored without selecting both Units.
• Information on restrictions will be displayed in the Information Area in the PLC Backup Tool if the
data to be stored includes a Unit that has restrictions on backup. Check the information on restric-
tions and take the required countermeasures. The control system may operate unexpectedly
when the equipment is operated after the data is restored
• Before restoring data during PLC operation, be sure that there will be no problem if PLC operation
stops. If the PLC stops at an unexpected time, the control system may operate unexpectedly.
• Be sure to turn the PLC power supply OFF and then back ON after restoring data. If the power is
not reset, the system may not be updated with the restored data, and the control system may
operate unexpectedly.
• Data on forced status can be backed up but it cannot be restored. Perform the procedure to force-
set or force-reset bits from the CX-Programmer as required before starting operation after restor-
ing data that includes forced status. Depending on the difference in the forced status, the control
system may operate unexpectedly.
• If a symbol or memory address (only symbols are allowed for ST programming) is specified for the
suffix of an array variable in ladder or ST programming, be sure that the specified element number
does not exceed the maximum memory area range.
Specifying an element number that exceeds the maximum range of the memory area specified for
the symbol will result accessing data in a different memory area, and may result in unexpected
operation.
• If a symbol or address is specified for an offset in a ladder diagram, program so that the memory
area of the start address is not exceeded when the offset is specified indirectly using a word
address or symbol.
If an indirect specification causes the address to exceed the area of the start address, the system
will access data in other area, and unexpected operation may occur.
28 CJ2 CPU Unit Software User's Manual