Block polling data communication system having optimum block

Abstract

An improved data communication system in which a block polling of a plurality of terminal blocks is first carried out, thereafter, a terminal polling of terminals in the terminal block(s) from which a response to the block polling has been issued is carried out. The data communication system includes a center office, a cable and a plurality of terminals which can be grouped in a plurality of terminal blocks. The center office includes a MODEM, a block polling unit, a response monitor unit for detecting a data transfer request signal from the terminal blocks during the block polling, and a terminal polling unit which sequentially effects a polling of terminals in the terminal block from which the request signal has been issued. The center office further includes a unit for determining optimum terminal numbers for the respective terminal blocks and allocating terminals in the respective terminal blocks in response to the data transfer request signals from the terminals during the terminal polling, to minimize a total polling time. The block polling unit and the terminal polling unit then carry out their respective pollings on the basis of the newly allocated terminal blocks and terminals.