TRANSMISSION LINE DUPLEX SYSTEM

PURPOSE:To prevent a token from being received over both transmission lines when the length of each token is shorter than a time length of a distance difference of the transmission lines by delaying a signal arrived first so as to give a same phase to that of the signal generated on the other transmission line. CONSTITUTION:A counter circuit 9 starts counting while receiving a state of a signal line S11 when a head (SD) of a signal on a signal line 1 comes first and stops counting when a head SD of a signal on a signal line S2 comes. The result of count is latched by a latch circuit 10 and given to a shift register circuit 11 whose shift length is variable as a shift length. Thus, the signal on the signal line S1 has the same phase as the phase of the signal on the signal line S2. When an SD comes on one signal line and no SD is generated on the other signal line within a time equivalent to a maximum delay time width, the circuit 3 generates a signal S19 to reset D flip-flops 7,8 and to stop the operation of counters 9,12 and the result is given to the shift register 11 whose shift length with a maximum delay time width is variable.