| 摘要 |
PROBLEM TO BE SOLVED: To provide an operation monitor of data terminal in which flow control of data communication can be carried out using a smaller number of signal lines and the operational conditions of a data terminal or the connection state of a connector at the interface can be monitored. SOLUTION: Data circuit terminating equipment 11 is connected with a data terminal 12 through a serial interface and an ER signal of the DTE 12 is switched back at the connector part of the DCE 11 and then connected with the DR and CD of the DTE 12. The ER signal is branched and inputted to a NOT gate 14, the output therefrom is inputted to an OR gate 15 together with an SD signal and the logical sum thereof is inputted to a CPU 16 together with RS, CS and RD. When operation of the DTE 12 is interrupted, the OR gate 15 delivers an ON output and operational interruption of the DTE 12 or falling off of the connector can be detected from duration of ON state.
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