| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a memory backup device and a programmable controller having the memory backup device which accurately detects the voltage drop of a battery before the battery becomes completely exhausted and urges a user to replace the battery, thereby preventing the battery backup operation of a memory from being interrupted because of the exhaustion of the battery. <P>SOLUTION: A memory backup device comprises: backup continuation means for continuing backup using a battery for a predetermined period after a main power supply is turned on; and battery voltage detection means for detecting a battery voltage during the continuation period, comparing it with a predetermined threshold value, and outputting the comparison result. <P>COPYRIGHT: (C)2012,JPO&INPIT |
