
APPENDIX
B–63525EN/02
C. BOOT SYSTEM
935
CAUTION
1 Action to be taken when an SRAM parity error is detected during backup of SRAM in the boot
system
The SRAM area of each CNC shipped from the factory is cleared and is free of parity errors.
However, shock applied to the CNC during transportation may cause a parity error in the SRAM
area. A parity error may also occur in the SRAM area when the CNC was kept switched off for
one year or longer, and the battery has been exhausted. If a parity error occurs in the SRAM
area, the data held in the SRAM area is not guaranteed. However, the CNC does not always
use the entire SRAM area. A parity error is not detected by hardware unless the part containing
the error is read. Therefore, if a parity error occurs in an area not accessed by the CNC, the
CNC may operate normally. The SRAM backup function of the boot system reads the entire
SRAM area. So, a parity error may occur in the middle of backup operation even when the CNC
has operated normally. In this case, the SRAM data of the CNC is not guaranteed, and the data
cannot be backed up using the SRAM backup function of the boot system. Nevertheless, the
CNC may operate normally. So, it is recommended that necessary data be backed up using
the Floppy Cassette or Handy File, data all clear operation be performed, then the backed up
data be restored in the CNC. Once all clear operation is performed, the parity error can be
removed. Then, the SRAM backup function of the boot system can be used.