10 CPU Unit Functions
10-40
CJ2 CPU Unit Software User’s Manual
z Operations after Power Is Interrupted during Automatic Backup
• If the power is turned OFF when there is a Battery installed in the CPU Unit and when only ladder
tasks are being edited online, the status prior to the power interruption will be restored the next time
the power is turned ON. Be careful, however, of the following points.
• More time will be required to start the CPU Unit.
• Even if there is a Battery in the CPU Unit, always be sure that the backup operation has been
completed before turning OFF the power supply if the CPU Unit will be left unpowered for an
extended period of time.
• The amount of time required to back up data (the time the BKUP indicator will be lit) will depend on
the size of the user program, as shown in the following table.
Note The BKUP indicator will be lit when power is supplied to the CPU Unit.
Precautions for Correct UsePrecautions for Correct Use
• Automatically back up the user program and parameter data to flash memory when they are
written to the CPU Unit. I/O memory (including the DM, EM, Holding, and Auxiliary Areas),
however, is not written to flash memory. The DM, EM, and Holding Areas can be held during
power interruptions with a battery. If there is a battery error, the contents of these areas may
not be accurate after a power interruption. If the contents of the DM, EM, Holding, and Auxil-
iary Areas are used to control external outputs, prevent inappropriate outputs from being made
whenever the Battery Error Flag (A402.04) is ON.
• A backup memory error (non-fatal) will occur if an error in the CPU Unit backup memory is
detected. If this error occurs, data will not be restored the next time the power supply is turned
ON, and a memory error may occur. Therefore, it is recommended to save the data before
turning OFF the power.
Automatic backup timing Applicable data
Operation after power interrup-
tion
While a program is being trans-
ferred
User program • The data will be lost.
• A memory error will occur the
next time the power is turned ON.
During online editing User program:
• Ladder tasks
• The changes made during online
editing will be reflected the next
time the power is turned ON. (If
there is no Battery, however, the
changes will not be reflected and
a memory error will occur.)
User program:
• ST tasks
• SFC tasks
• FB definitions
• SFC actions and transitions
• The contents of the online editing
will be lost.
While the PLC Setup is being trans-
ferred, the I/O tables are being
transferred, the I/O tables are being
created or cleared, the routing
tables is being transferred, or Spe-
cial I/O Unit settings are being
transferred.
Parameters • The data will be lost.
• A memory error will occur the
next time the power is turned ON.
User program size
Backup processing time
MONITOR mode PROGRAM mode
100 Ksteps 20 s (cycle time of 3 ms) 3 s
250 Ksteps 47 s (cycle time of 7 ms) 6 s
400 Ksteps 75 s (cycle time of 11 ms) 10 s
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