A slave device that is connected to a controller which is a master device via a network, and the slave device includes a communication port to which an actual device is connected, the slave device comprising: a high-order communication control unit, configured to control communication with the controller via the network; an acquisition unit configured to acquire identification information of the actual device connected to the communication port from the actual device; an instruction information acquisition unit configured to receive a settings instruction from at least one of the controller and a support tool connected to the controller via the network through the high-order communication control unit, wherein the settings instruction is an instruction for generating configuration settings information including identification information of devices scheduled to be connected to the communication port, a generation unit configured to generate the configuration settings information on the basis of the identification information acquired by the acquisition unit; a collation unit configured to collate the identification information acquired by the acquisition unit with the identification information included in the configuration settings information; and a device communication processing unit configured to acquire a collation result of the communication port from the collation unit, characterised in that the instruction information acquisition unit is configured, upon reception of the settings instruction, to instruct the collation unit to pause the collation process, and to instruct the generation unit to generate the configuration settings information, so that the collation unit does not collate the identification information acquired by the acquisition unit with the identification information included in the configuration settings information to avoid that the configuration settings information is updated using the identification information acquired by the acquisition unit even when it is necessary for the collation unit to execute the collation, and the device communication processing unit is configured to maintain the communication in the communication port when the collation result of a collation normality is acquired and to stop the communication in the communication port when the collation result of a collation abnormality is acquired. a high-order communication control unit, configured to control communication with the controller via the network; an acquisition unit configured to acquire identification information of the actual device connected to the communication port from the actual device; an instruction information acquisition unit configured to receive a settings instruction from at least one of the controller and a support tool connected to the controller via the network through the high-order communication control unit, wherein the settings instruction is an instruction for generating configuration settings information including identification information of devices scheduled to be connected to the communication port, a generation unit configured to generate the configuration settings information on the basis of the identification information acquired by the acquisition unit; a collation unit configured to collate the identification information acquired by the acquisition unit with the identification information included in the configuration settings information; and a device communication processing unit configured to acquire a collation result of the communication port from the collation unit, characterised in that the instruction information acquisition unit is configured, upon reception of the settings instruction, to instruct the collation unit to pause the collation process, and to instruct the generation unit to generate the configuration settings information, so that the collation unit does not collate the identification information acquired by the acquisition unit with the identification information included in the configuration settings information to avoid that the configuration settings information is updated using the identification information acquired by the acquisition unit even when it is necessary for the collation unit to execute the collation, and the device communication processing unit is configured to maintain the communication in the communication port when the collation result of a collation normality is acquired and to stop the communication in the communication port when the collation result of a collation abnormality is acquired.