| 摘要 |
An electronic signaling device and a loop system incorporating at least one of the devices is described. The device is powered by the loop current and voltage and includes circuitry which enables it to function both in the mode where loop current is interrupted and when it is not. Each device has its own unique ID which is interrogated by the circuitry and which includes further circuitry for interrupting the loop current so that the unique ID can be transmitted to a remote location. Circuitry is provided to determine whether or not other loop activity is taking place before the device transmits its ID. Pause circuitry is provided to create distinguishable intervals between each digit of the ID and between each, successive transmission of a complete ID. Shut down circuitry is provided to return the device to its quiescent state after it has transmitted its ID or when an anomaly occurs.
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