| 摘要 |
PURPOSE:To multiplex a control signal on a data signal by providing an interface converting circuit comprising a multiplexer circuit, a demultiplexer circuit, a synhronizing circuit and a digital PLL circuit to each of a data exchange network and a data terminal device respectively to reduce the number of signal lines. CONSTITUTION:A data transmission system is constituted of a terminal device DTE and a line terminator DCE, and the multiplexer circuit 2 of the interface converting circuit (2) of the DCE multiplexes the information of R and I lines of an X.21 interface. Further, the multiplexer circuit 1 of the interface converting circuit (1) of the DTE multiplexes the information on T and C lines in the interface and transmits it to a line T'. Then the conversion and transmission of the information are controlled by respective synchronizing circuits 1, 2, the number of signal lines is reduced and the control signal is multiplexed on the data signal. |
