A system includes communications nodes, respectively having a sensor; and a communications apparatus that simultaneously requests the communications nodes to transmit sensor data. A first communications node among the communications nodes, when determining that among a first state where the communications apparatus includes the first communications node when requesting transmission and a second state where the communications apparatus excludes the first communications node when requesting transmission, the first communications node is in the second state: determines whether a predetermined difference is present between a predetermined value and the sensor data of the first communications node, and transmits a notification signal that notifies the communications apparatus of the predetermined difference, when determining that the predetermined difference is present.