Abstract: A network-configuration-information generation method generates information indicating a network configuration of a network system defined by a plurality of communication devices and a plurality of networks. The method includes: a step in which at least one of the communication devices generates and stores network-configuration information defined as a pair of a network name of a network to which the at least one communication device belongs and a network name of a network adjacent to the network to which the at least one communication device belongs; and steps in which when each communication device receives, from another communication device, the network-configuration information stored in the other communication device, each communication device stores the received network-configuration information.

Abstract: A network-configuration-information generation method generates information indicating a network configuration of a network system defined by a plurality of communication devices and a plurality of networks. The method includes: a step in which at least one of the communication devices generates and stores network-configuration information defined as a pair of a network name of a network to which the at least one communication device belongs and a network name of a network adjacent to the network to which the at least one communication device belongs; and steps in which when each communication device receives, from another communication device, the network-configuration information stored in the other communication device, each communication device stores the received network-configuration information.

Abstract: A master-slave communication system (1) includes communication devices (100A to 100D) each operable as a master or a slave. Each of at least two (100A to 100C) of the communication devices that operates as slaves includes a down-state detection period storage (120) that stores a down-state detection period set shorter for a slave with a higher priority in selecting a new master among the slaves. A master presence determiner (140) determines whether a master is present based on whether the communication device receives, after receiving a signal from a master and before the down-state detection period elapses, a new signal from a communication device operating as a master. An operation switch (160) switches an operation of the communication device to an operation as a master when the master presence determiner (140) determines that a master is absent.