a data frame which is transmitted from a transmitting station is provided with an individual response part having response bits corresponding to all stations on a network , so that the transmitting station initializes the individual response part in data transfer . each receiving station outputs its own state to a prescribed position of the individual response part , and the transmitting station monitors the individual response part . thus , it is possible to correctly confirm whether or not the data is normally transferred to those of the receiving stations which are to receive data .