| 摘要 |
A communications system for an elevator system has a master control unit located close to the lift controller and connected via a bus to a number of local modules, each connected to one or more announcement devices. The announcement devices may be of various types including alphanumeric display of elevator position or other messages, lanterns indicating direction of travel, electronic gongs and passing chimes. The bus consists of only two conductors which carry both power and output signals from the master control unit to the respective local modules, the signals being encoded by modulation of the power supplied. The system reduces the amount of wiring required for new installations of elevator systems and also facilitates retrofitting to existing systems to install dot matrix display devices or audible announcement devices without the need for additional wiring.
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