| 摘要 |
PURPOSE:To miniaturize a secondary station by comparing a reception data from a primary station with an operation value, sending the data in case they are coincident to the secondary station and sending a dummy signal from the primary station if no data is sent from the secondary station so as to use only a 2-core transmission line. CONSTITUTION:The primary station 1 sends a parameter A1 to the secondary station 2, the data are given to an operation hold circuit 27, where the relation of operation value=A(n)X2-1 is obtained. The primary station 1 sends a data signal to the secondary station 2, a comparator 29 discriminates whether or not the operation value of the operaton holding circuit 27 is equal to the count of a reception counter 28, in this case, 1, and outputs a reception data T1 because only the secondary station 2 gives an equal value. The other secondary stations await the next data signal. When the data T2 is sent next, since the data is equal to the operation value(=3) in the operation holding circuit 27 of the secondary station 3, only the secondary station 3 sends a data signal R2 and outputs the reception data T2. Similarly, the data is sent. When a specific secondary station is faulty and no data is sent, the result is sent to a dummy signal transmission circuit 20 to continue the transmission.
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