
160
3.27.1
Latch data backup
The following two methods are available for backing up latch data to the standard ROM.
• By contacts
• By remote operation
(1) Execution by contacts
(a) Setting method
Configure the setting for "Latch Data Backup Operation Valid Contact". (The devices applicable to a contact are
X, M, and B.)
Project window
[Parameter]
[PLC Parameter]
[PLC System]
(b) Execution method
Backup starts at the rise of a contact (off
→
on). After backup, the BAT.LED of the CPU module flashes (green),
indicating that the CPU module is in the standby status ready to be powered off. The execution status of
backup operation can be checked by SM671 or SD671 to SD675.
(c) Precautions
• To set the CPU module to the RUN status from the standby status, power it on again or reset after the
backup operation is complete.
• The status of latch data backup valid contact to the standard ROM is checked at execution of the END
instruction. Therefore, data are not backed up even if a contact is repeatedly turned on and off (on
→
off
→
on, or off
→
on
→
off) in one scan.
• When the latch data backup valid contact to the standard ROM is set to X, and the CPU module is
powered off and then on or is reset without turning off the contact, the data cannot be backed up unless
the latch data backup valid contact to the standard ROM is turned off and then on again.
• The latch data backup start contact to the standard ROM is set to M or B, and data are backed up by
turning off and then on the contact the data cannot be backed up unless the latch data backup valid
contact to the standard ROM is turned off and then on again.
Set a contact.
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