Yaskawa MP920 User's Manual Design - Manual (Page 476)

11 Maintenance and Inspection
11.2.1 Battery Life
11-4
11.2 CPU Module Battery
The CPU Module has one replaceable built-in battery, which is used to prevent the programs
and data stored in the memory from being lost when a power failure occurs (i.e., when the
power supply to the CPU Module is interrupted).
11.2.1 Battery Life
The built-in battery can retain the contents of the memory until the total time of power inter-
ruptions reaches one year. The warrantee period of the battery is five years from the date of
purchase. These values, however, differ according to the operating conditions, including the
ambient temperature.
If the BAT indicator on the CPU Module lights, replace the battery with a replacement bat-
tery within two weeks. Any delay in battery replacement will result in the programs and data
stored in the memory being lost.
If the power supply is left OFF for one hour or more while the battery voltage badly decreases or the
battery is not connected, the programs and data stored in the memory will be lost. Replace the battery
with a new battery within one hour.
The following case is assumed for the above.
• The BAT indicator was lit once before a holiday and the power has been turned OFF during the
holiday. When the power is turned ON after the holiday, the BAT indicator lights again.
11.2.2 Battery Replacement
This section describes how to replace the battery.
„ Preparations
Saving the Memory Contents
Before replacing the battery, save the programs and data from the memory of the CPU Mod-
ule to floppy disks or a hard disk. The saved programs and data will be used if the programs
and data are accidentally deleted during battery replacement.
IMPORTANT