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CP1E CPU Unit Instructions Reference Manual(W483)
Be sure to sufficiently confirm the safety at the destination when you transfer
the program or I/O memory or perform procedures to change the I/O memory.
Devices connected to PLC outputs may incorrectly operate regardless of the operat-
ing mode of the CPU Unit.
With an E-type CPU Unit or with an N/NA-type CPU Unit without a Battery, the con-
tents of the DM Area (D) *, Holding Area (H), the Counter Present Values (C), the sta-
tus of Counter Completion Flags (C), and the status of bits in the Auxiliary Area (A)
related to clock functions may be unstable when the power supply is turned ON.
*This does not apply to areas backed up to EEPROM using the DM backup function.
If the DM backup function is being used, be sure to use one of the following methods
for initialization.
1. Clearing All Areas to All Zeros
Select the Clear Held Memory (HR/DM/CNT) to Zero Check Box in the Startup
Data Read Area in the PLC Setup.
2. Clearing Specific Areas to All Zeros or Initializing to Specific Values
Make the settings from a ladder program.
If the data is not initialized, the unit or device may operate unexpectedly because of
unstable data.
Execute online edit only after confirming that no adverse effects will be caused
by extending the cycle time.
Otherwise, the input signals may not be readable.
The DM Area (D), Holding Area (H), Counter Completion Flags (C), and Counter
Present Values (C) will be held by the Battery if a Battery is mounted in a CP1E-
N/NAD- CPU Unit. When the battery voltage is low, however, I/O memory
areas that are held (including the DM, Holding, and Counter Areas) will be unstable.
The unit or device may operate unexpectedly because of unstable data.
Use the Battery Error Flag or other measures to stop outputs if external out-
puts are performed from a ladder program based on the contents of the DM
Area or other I/O memory areas.
Sufficiently check safety if I/O bit status or present values are monitored in the
Ladder Section Pane or present values are monitored in the Watch Pane.
If bits are set, reset, force-set, or force-reset by inadvertently pressing a shortcut key,
devices connected to PLC outputs may operate incorrectly regardless of the operat-
ing mode.
CautionCaution