Method of judging communication stability of network system and master unit, slave and repeater therefor

摘要

A method of judging communication stability is provided for a network system including a master unit forming a programmable controller and a slave connected to a network. The master unit transmits to the slave a distorted test pattern formed by distorting a standard test pattern to a specified distortion level. If this distorted test pattern is normally received by the slave, a response is returned from the slave to the master unit. If the mater unit receives this response normally, it is judged that this network system has communication stability corresponding to this specified distortion level.