| 摘要 |
PURPOSE:To obtain a compact and low-cost power failure detector without degrading the precision of power failure detection by writing and reading repeatedly data having a specific pattern for power failure detection in a data gathering system which is not protected from power failure. CONSTITUTION:In the monitor and control system where a master station 1 gathers data of slave stations 2-n, each slave station which is triggered by polling from the master station 1 reads data having a specific pattern for power failure detection which is written in a memory and transmits this data to the master station and writes data and repeats this operation. If power failure occurs between polling and polling, power failure information is transmitted to the master station, and the slave station writes said data again. If power failure occurs in the slave station at the polling time, data for power failure detection is not transmitted to the master station, and the master station finds the occurrence of power failure. |
