YOKOGAWA FA-M3 VITESSE F3CX04-0N, User Manual

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C4-1
IM 34M06H63-01E 1st Edition : July, 2003-00
C4. Disable Backup Function
The Disable Backup Function (NBKUP) parameter can be used to suspend storing
of parameters to the EEPROM.
The module has two types of parameters: stored and non-stored. Stored parameters
preserve their data even when the module is powered down. For details on whether a
parameter is stored or non-stored, see the individual parameter table or the list of
registers.
The default value of the Disable Backup Function (NBKUP) parameter is 0 (backup). With
NBKUP=0, if a stored parameter is changed, its data is written to the EEPROM and thus,
preserved even if power supply is turned off.
As there is a maximum limit to the number of write operations (approx. one million at 25

C
or lower, or 100,000 within temperature range) allowed for the EEPROM, beware not to
exceed the limit. Once the limit is reached, further writing is not allowed and a hardware
failure occurs.
If the Disable Backup Function (NBKUP) parameter is set to 1 (no backup), changes to
stored parameters are not written to the EEPROM. Thus, when the module is turned off
and turned on again, the parameters contain the previous stored values.
CAUTION
Do not attempt to change the value of the Disable Backup Function (NBKUP) parameter
from 1 (no backup) to 0 (backup) by writing to the parameter.
To reactivate the backup function, simply switch off and then switch on the module. Since
the NBKUP parameter is not a stored parameter, its value will reset to 0 (backup) after
powering up.
TIP
If you update some parameters after changing the NBKUP parameter to 0 (Backup), and then switch off
and switch on the module, you may find that not all parameter values are what you expect. This is
because the module stores parameters only when they are changed.
Table C4.1 Disable Backup Function Parameter
Data Position
Number
Symbol Description
Unit Data Range
Default
Value
Attribute Stored
75 NBKUP
Disable Backup
Function
None 0: Backup
1: No backup
0 RW −