| 摘要 |
PURPOSE:To improve the utilizing efficiency of a loop network and to reduce the data transmission time of a slave node by providing a dead frame transmission function to a master node and a dead frame detection function or the like to the slave node. CONSTITUTION:A transmission frame control circuit 42 provided to the master node 1 gives a data to be sent to the slave node 2 to a transmission frame representing the transmission from the master node and sends the result as an information frame. In this case, a comparator 10 compares the number of receptible information frames by the node 1 with the number of dead frames left in the loop network and gives the result to the circuit 42. When the number of receptible information frame in more then the dead frame number, the circuit 42 sends the dead frame to the node 2. Then a dead frame is detected via the dead frame detection circuit 37 of the node 2, the data to be sent to the node 1 is given to generate the information frame, which is sent. Thus, the data transmission time of the node 2 is reduced and the utilizing efficiency of the loop network is improved.
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