| 摘要 |
The system supplies the transmission channel with a control signal which has 2 different signal amplitude signal zones (J1, J2) spaced from zero, either side of a signal amplitude zone which is also spaced from zero and corresponding to 2 respective switch conditions. Detected signal values which lie outside either of the first 2 signal amplitude zones (J1, J2) are evaluated to provide a fault or alarm signal. Pref. the digital control signal is used for controlling a microprocessor (M) with the control signal pref. transmitted via an optical fibre transmission path (4).
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