METHOD FOR DETECTING ILLEGAL ACCESS IN MULTI-ACCESS

摘要

PURPOSE:To easily detect an illegal access, by setting a numeric value different with each other obtained by performing the arithmetic processing of a station number, and a common numeric value at each slave station, as the initial value of a random number, and also, performing the arithmetic processing at a control station similarly. CONSTITUTION:The slave stations 21-27 can obtain the numeric values different with each other by performing the exclusive OR of the random number distributed from the control station 1, and the station number of said station, at each slave station. The arithmetic calculation of the exclusive OR at each slave station is performed at the control station 1 similarly for each slave station, and it is possible to confirm the currently generated random number of the slave station. Since the initial value of the slave station can be recognized by the control station by providing a random number generator used in common for each slave station, the control station can recognize the generated random number of the slave station, Therefore, when the control station generates a specified probability reference value, the control station can predict the slave station which may issue a request signal corresponding to the value. In this way, it is possible to confirm the illegal access of the slave station, by detecting the request signal from the slave station other than the slave station predicted by the control station.