COMMUNICATION METHOD FOR BUILDING MANAGEMENT EQUIPMENT

PURPOSE:To minimize the amt. of traffic in a bus form transmission line by reducing communication load even when the number of devices is increased in the communication method of sending data in a spread way via the bus form transmission line by a central processing unit, man-machine devices and data collection devices. CONSTITUTION:When a central processing unit 1 and man-machine devices 2-1, 2-2 receive normally communication data whose serial numbers are consecutive from a data collection device 4, they do not reply the data device 4 but continue the communication and the man-machine device 2-2 estimates leaked reception of communication data due to missing in serial numbers of the communication data to be received from the data collection device 4 and the man- machine device 2-2 recognizing leaked reception replies an error replay with respect to the leaked reception only to the data collection device 4 sending the communication data whose serial number is missing.