Bus-method communication network system capable of seizing transmission right by using timer means at each station

In a bus-method communication network system comprising a bus-method transmission path and a plurality of stations commonly connected to said transmission path for mutual communication, said stations being assigned with station numbers different from one another, a specific one of said stations having an exclusive transmission right to access to said transmission path at a specific time without the other stations being permitted access to said path, said specific station having means for transmitting an abort signal representative of abandonment of said exclusive transmission right to said transmission path so that one of the other stations can then seize the exclusive transmission right by detecting said abort signal, the improvement wherein:

• said specific station has, as a specific station number, an assigned station number and said abort signal comprises synchronization information and the specific station number, each one of said stations comprising:
• station number memorizing means for storing, as a preassigned station number, a corresponding one of said assigned station numbers;
• receiver means coupled with said transmission path for receiving a transmission signal on said transmission path;
• abort signal detecting means for detecting said abort signal in said transmission signal when received by said receiver means and for extracting said specific station number in said abort signal as detected, said abort signal detecting means producing an abort detection signal and an address signal representative of said specific station number as extracted;
• time calculating means coupled with said station number memorizing means and said abort signal detecting means for calculating a first time period depending on said extracted specific station number and said preassigned station number to produce a first time data signal representative of said first time period;
• first time measuring means responsive to said first time data signal for measuring time to produce an output, as a first enabling signal, when said first time period elapses;
• and
• seizing decision means responsive to said first enabling signal for deciding permission of seizure of the exclusive transmission right to produce a seizing signal when the permission is decided, wherein one of the stations other than said specific station can newly seize the exclusive transmission right.