| 摘要 |
PROBLEM TO BE SOLVED: To provide a programmable logic controller capable of correcting current time by a simpler and surer method as compared with a conventional method.SOLUTION: When an output voltage of an RTC power supply 40 for supplying electric power to an RTC 37 installed in a body 2 of a PLC is lowered, current time of the RTC 37 is corrected by time data supplied from an RTC of an operation module 3 connected to the body 2. Since the RTC of the operation module 3 can clock the current time without receiving a radio wave indicating time, the current time of the PLC can be corrected even in a site such as a plant where a radio wave does not reach. Further, the current time of the RTC 37 can be corrected by time data supplied from the RTC of the operation module 3 without connecting a terminal device to a GPS receiver via a network. Accordingly, time information of a PLC 1 can be corrected by the simpler and surer method as compared with the conventional method. |
