| 摘要 |
PURPOSE:To attain the normal signal transmission to a slave side even at a distorted signal waveform not only at power interruption to a master side by connecting a slave side local network to a master side local network in cascade in case the signal waveform is normal and applying connection by the slave side local networks in case of fault. CONSTITUTION:When the waveform of a signal Q appears in a communication line 31, a one-shot circuit 30 sends a transmission state signal P of a high level. Thus, an NPN transistor (TR) 33 is conductive to energize a relay coil 34. Then the output contact 35 is connected to a contact (a), the slave side local network N1 is connected in cascade with the master side network N2. If the waveform of the signal Q is distorted due to the power interruption to devices 10-1-10-n of the master side N2, the one-shot circuit 30 sends a low level transmission state signal P after a prescribed period T. Then the TR 33 is nonconductive, the energizing state of the relay coil 34 is lost, the contact 35 is turned to a terminal (b), the connection between the slave side N1 and the master side N2 is released and a signal is sent in the slave side N1 among devices 1-1-1-n.
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