| 摘要 |
A bus management node 11 has a register for channels in use REG1 and.a b us capacity register REG2. Before starting the synchronous communication, each node 12 transmits a read-out command to the register for channels in use REG1 and the register for channels in use REG1 in order to read out their contents for ascertaining the number of the un-used channel and the residual capacity. If there is any un-used channel and any residual bus capacity, the node 12 transmits write commands to these registers REG1 and REG2 so that the number of the channel to be in use and the capacity of the bus to be in use will be stored in the register for channels in use REG1 and the bus capacity register REG2. When carrying out the writing in REG1 an d REG2, the node 12 compares read channel state information and read bus sta te information read out by the read-out command with channel state information and bus state information in REG1 and REG2 respectively. If the read channel information and the bus state information are identical to the channel state information and the bus state information in REG1 and REG2 respectively, it writes new channel information and new bus state information. This makes it possible to elimina te the possibility of wirting by other nodes.
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