| 摘要 |
PURPOSE:To select a master station surely in a short time, by locating a communication station in the order of addresses to a direction of signal flowing, transmitting a master station selecting signal with an original station address and selecting the master station. CONSTITUTION:A ring communication line 1 is provided with a station ST2 having addresses of K=1-255 and a coupling section of a communication line 2. A signal transmitted from the line 1 is inputted to a communication control LSI7, and an interruption signal is transmitted to a DMA9 at the same time and communication information is transmitted from the LSI7 to an RAM 14 not through a CPU11. When the LSI7 is at on-loop mode, the communication information is given to an ST at the downstream with a delay by 2-bit. If the communication information is not received for a prescribed time, all the STs transmit a master selection signal and receive signals from adjacent STs. In this case, each ST compares a transmission original address with the master station selecting signal with the address of the ST itself, and when the ST address of itself is smaller, the ST itself is taken as a master station and a GA signal is transmitted to restart communication. |
