| 摘要 |
Data communication circuit between multiple transmitters is provided, which includes a ring signal detecting part (10) for detecting a ring signal from a telephone line (1), a relay driving circuit (12) for driving a relay switch (11) according to a control signal output from a microcomputer (15) to form a data transmitting/receiving path, an amplifier part 913) for amplifying an input/output signal to a predetermined level, a DMF transmitting/receiving path for converting data between the microcomputer (15) and the amplifier part (13), a communication control part (20) having a waveform synthetic circuit (30) for controlling the data transmitting/receiving between twisted-pair cable (5) and the telephone line (1), a signal transmission circuit (50) for repeating the digital data between the twisted-pair cable (5) and the microcomputer (15) and supplying power supply to an external machine, and a signal converter (60) for modulating the digital signal by a modem (43) to communicate with connected external machine, wherein data are converted into a proper signals for the respective transmission media by the communication control part and the signal converter so that the data communication becomes possible with respective connected machines.
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