| 摘要 |
PURPOSE:To detect a collision even when a modulation system is changed, by providing a monostable mltivibrating circuit which operates synchronizing with the transmission of data and a communication control means which detects whether data is present on a transmission medium or not from the output of the monostable multivibrating circuit. CONSTITUTION:The monostable multivibrating circuit 1 is driven repeatedly synchronizing with the rising of transmit data and its output is held in the firstly driven state. This state is reset t1 after the transmit data is all expelled from the transmission medium 2. A communication control circuit 4 monitors the output of the monostable multivibrating circuit 1 through a pulse width selecting circuit 3 to detect whether the transmit data is present on the communication medium or not. The time constant t1 of the monostable multivibrating circuit 1 is varied according to terminals to give the terminals priority, suppressing the probability of collision low. |
