| 摘要 |
In industrial plants and electricity supply systems, central control is in most cases necessary due to the complexity of the processes. This is done digitally today, and it is necessary to lock and/or unlock the individual inputs and/or outputs on commissioning of the plant or in the case of inspection work. This is done by means of a method in which it is possible to switch between "locked" and "unlocked" operation by means of a central switch. In "unlocked" operation, individual inputs and/or outputs of the central controller can be connected to the plant to be controlled, or disconnected, by an externally connected input device. Those inputs and/or outputs which are not connected to the plant can be optionally set to one of the logic levels. According to the figure, this method can be implemented either with the aid of a programme in the central controller or by means of digital chips.
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