PURPOSE: To achieve that times on individual clocks coincide with each other by a method wherein one out of two clock means is set as a reference clock, time data is transmitted from one clock means as a reference to the other clock means and the present time on the other clock means is corrected automatically on the basis of the time data which has been received.
CONSTITUTION: A CPU and a calendar IC with which a reader part 1 is provided are set respectively as masters, and a CPU and a calendar IC with which a core part 10 is provided are set as slaves. Consequently, the master calendar IC in the reader part 1 is used as a reference clock. After the master CPU has judged that the power supply of the core part 10 has been turned on, it exchanges a command with the slave CPU regarding a time rewrite operation. After a rewritable command has been received, the master CPU reads out the time of the master IC and sends it to the slave CPU. The slave CPU receives it, rewrites the time of the slave calendar IC and reports the completion to the master CPU. Consequently, the burden to set the time of each calendar IC by an operator can be reduced.
YOSHIHARA KUNIO
SAKAI MASAKI
UNNO KOICHI
ITO HIROHIKO
