Data comparison apparatus, data comparison method and safety system using the same

摘要

In a conventional computer control system required to have high safety that has two CPUs in perfect synchronization with each other and a failsafe comparison circuit that detects a fault of the CPUs by checking whether the data output from the CPUs are matched or unmatched, the comparison circuit cannot precisely compare the data if the output data from the two CPUs are out of synchronization. A data comparison apparatus has a synchronization signal generating circuit 10 that generates a synchronization signal 3 based on data 1a and 1b sent from a plurality of data sources A and B, a synchronization loss detecting circuit 20 that generates a synchronization adjustment signal 5 based on the synchronization signal 3, and a synchronization adjusting comparison circuit 30 that adjusts the comparison timing based on the synchronization adjustment signal 5 to compare the data 1a and 1b. The data comparison apparatus compares data 1a and 1b sent from the two data sources A and B that can be out of synchronization.