| 摘要 |
To display the operational events of a plant to be controlled and/or to be monitored on as small as possible a display area, it is provided to illuminate, as required, the event fields, associated with the individual plant elements, of the display area of the optical fibres (LL). These optical fibres (LL) are to be illuminated via associated light-emitting diodes (LED). Each light-emitting diode is associated with an event line (ML) via which the operating state of the light-emitting diode is to be transmitted to a remote control station. This event line is connected, in the vicinity of the in each case associated light-emitting diode, via a high impedance (via R) to a potential (H) which identifies the deenergised state of the light-emitting diode. If the light-emitting diode is switched on, a potential (L) identifying the energised state of the light-emitting diode is impressed on the event line (ML). This potential is taken either from the feed circuit of the light-emitting diode (LED) between a switch (S) and the light-emitting diode, via an optocoupler (OK) controlled at the input end by the feed current of the light-emitting diode or switched via an optocoupler which is controlled by the light-emitting diode itself. <IMAGE>
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