Omron CJ - REFERENCE MANUAL 02-2010 Reference Manual page 34

PRECAUTIONS
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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, care-
fully check the safety of the devices at the connection target before
restarting the Unit.
• If a symbol or memory address (only symbols are allowed for ST pro-
gramming) is specified for the suffix of an array variable in ladder or ST
programming to indirectly specify the element number, be sure that the
element number does not exceed the maximum memory area range.
Specifying a element number that exceeds the maximum range of the
memory area specified for the symbol will result accessing data in a differ-
ent memory area, and may result in unexpected operation.
• Program so that the memory area of the start address is not exceeded
when using a symbol or address is used to specify the offset directly in a
ladder program.
If an indirect specification causes the address to exceed the memory area
of the start address, the system will access data in other area, and unex-
pected operation may occur.
• A CS1 or CJ1 CPU Unit program file (.OBJ) cannot be transferred directly
to a CJ2 CPU Unit using a Memory Card. It must first be converted for use
with a CJ2 CPU Unit using the CX-Programmer.
■ External Circuits
• Always turn ON power to the PLC before turning ON power to the control
system. If the PLC power supply is turned ON after the control power sup-
ply, temporary errors may result in control system signals because the
output terminals on DC Output Units and other Units will momentarily turn
ON when power is turned ON to the PLC.
• Install external breakers and take other safety measures against short-cir-
cuiting in external wiring. Insufficient safety measures against short-cir-
cuiting may result in burning.
• 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.
CS/CJ/NSJ Series Instructions Reference Manual (W474)