| 摘要 |
PURPOSE:To enable evasion of collision and recollision and reduce waiting time at the time of occurrence of coolision by detecting presence of collision by measuring the time difference of starting time of transmission and reception at each terminal and making preferential processing. CONSTITUTION:A CPU8 monitors a line of data sent from a receiving register 10 according to request for transmission, and when vacant rotation is detected, starts data transmission through a transmitting register 9, and at the same time, a time difference measuring circuit 11 measures time from start of transmission to start of receiving and reports to the CPU8. When transmission data coincide with receiving data at that time, the CPU8 stores the time difference. This time difference corresponds to time T of propagation of the signal from the transmitting circuit to receiving circuit. Counting of the time difference measuring circuit is started by starting of transmission, and stopped by starting of receiving. When this time difference is greater than previously stored time T, it is judged that there is no collision, and when shorter than the time T, it is judged that there is collision and transmission is interrupted at once. |
