| 摘要 |
PURPOSE:To automatically select the timing signal from the terminal unit in the next order and to relieve failures, by giving priority of switching for the external timing signal, for the stop of timing signal with failures in the terminal unit with priority. CONSTITUTION:The terminal units of N sets (where N>=2) are made to receive and give the data of multi-port via the modulation and demodulation unit providing the multiplex function and this multiplex channel is taken as 4-channels. Further, the external timing signals T1-T4 with priority of switching in advance are fed to the external timing signal input terminals 1-4, and the clock pulse C is fed to the common clock pulse input terminal 8. This timing switching circuit is provided with the switching control circuits 5-7 controlling the switching circuits 9-11 according to the priority, the 1st and 2nd signals T1, T2 are selected with the output of the signal T1 fed to the circuit 5 at the first step to output from the circuit 9. Similarly, the output selected at the pre-stage and the signals T3, T4 are selected at the circuits 10, 11 to output them from the output terminal 12. |
