PURPOSE: To perform transmission/reception of signals for each channel for a prescribed time, by turning on/off the signals of a plurality of data channels for definite time after inputting a start signal.

CONSTITUTION: The system provides a memory 3 storing the operating time data to addresses assigned to each channel, reference time generator 8 generating the reference signal train in a prescribed unit period at the same time as the start signal, memory 5 reading out the operating time data of the memory 3 through the 1st reference signal and storing it to the same address, operator 6 which reads out the time data of the memory 5, subtracts it from a specified value and produces an overflow signal when the result of the subtraction is zero, and a decoder 9 which decodes the address of the memory 5 and produces an output signal. A channel CH when the overflow signal from the operator 6 and the output signal from the decoder 9 coincide, is latched 10.