PURPOSE: To detect the deformation and missing of data and to restore the system by recording doubly information stored in EEPROM dividing it into two data blocks and detecting the data abnormality based on the sum check value.
CONSTITUTION: In the lapse of a prescribed time, a microprocessor μP2 starts a memory check, calculating the sum check according to the sum check arithmetic program in the A block of a memory EEPROM 3, when judged to be normal, executed the sum check according to the sum check arithmetic program in the B block of the memory EEPROM 3. On the other hand, when judged to be abnormal, it executes the sum check in the B block of the memory EEPROM 3, when judged to be normal, copies the data stored in each address of the data area 3DB to a data area 3DA. When judged to be abnormal, it is deduced that the both A and B blocks are abnormal so that the memory EEPROM 3 itself is judged to be abnormal and alarm is outputted outside.
SEKIGUCHI TOSHIO
KOYAMA ETSUTARO
KUBO TOMOHIDE
