DATA TRANSMISSION CONTROL SYSTEM IN MULTIDROP SYSTEM

摘要

PURPOSE:To reduce the load of a processor and then set up the data link, by storing the polling/selecting signals sent from a data processor at each data terminal device and then sending the signal showing the terminal number to the processor after recognizing the stored signal. CONSTITUTION:The master unit M functioning as a data processor is connected to the slave units 1-N functioning as a plural number of data terminal devices via the transmission lines A and B. Then the polling/selecting signals are transmitted successively to the units 1-N when the unit M is ready for reception. After storing this signal in each memory device m, each of the units 1-N recognizes the memory for transmission of the data and then transmits the signal showing the terminal number to the unit M via the common line B. Then the signal that designates the units 1-N is transmitted when the unit M reads the terminal number; while the polling/selecting is carried out in case the reading of the terminal number is impossible. Thus a data link is set up between the unit M and each of the units 1-N which wants to transmit the data to the unit M.