Omron CJ - 09-2009 Operation Manual page 42

Application Precautions
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• If, when using a CJ-series CPU Unit, the PLC Setup is set to specify using
the mode set on the Programming Console and a Programming Console
is not connected, the CPU Unit will start in RUN mode. This is the default
setting in the PLC Setup. (A CS1 CPU Unit will start in PROGRAM mode
under the same conditions.)
• 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.
• 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.
• Fail-safe measures must be taken by the customer to ensure safety in the
event that outputs from Output Units remain ON as a result of internal cir-
cuit failures, which can occur in relays, transistors, and other elements.
• Fail-safe measures must be taken by the customer to ensure safety in the
event of incorrect, missing, or abnormal signals caused by broken signal
lines, momentary power interruptions, or other causes.
• Interlock circuits, limit circuits, and similar safety measures in external cir-
cuits (i.e., not in the Programmable Controller) must be provided by the
customer.
• Do not turn OFF the power supply to the PLC when data is being trans-
ferred. In particular, do not turn OFF the power supply when reading or
writing a Memory Card. Also, do not remove the Memory Card when the
BUSY indicator is lit. 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.
• If the I/O Hold Bit is turned ON, the outputs from the PLC will not be
turned OFF and will maintain their previous status when the PLC is
switched from RUN or MONITOR mode to PROGRAM mode. Make sure
that the external loads will not produce dangerous conditions when this
occurs. (When operation stops for a fatal error, including those produced
with the FALS(007) instruction, all outputs from Output Unit will be turned
OFF and only the internal output status will be maintained.)
• The contents of the DM, EM, and HR Areas in the CPU Unit are backed
up by a Battery. If the Battery voltage drops, this data may be lost. Provide
countermeasures in the program using the Battery Error Flag (A40204) to
re-initialize data or take other actions if the Battery voltage drops.
• Always use the power supply voltages specified in the operation manuals.
An incorrect voltage may result in malfunction or burning.
• Take appropriate measures to ensure that the specified power with the
rated voltage and frequency is supplied. Be particularly careful in places
where the power supply is unstable. An incorrect power supply may result
in malfunction.
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