Patent ID: 7161261

Claim:
Control apparatus for a door-locking mechanism including an electrically-released latch for locking the door closed, which apparatus comprises: a processing unit having first and second data stream sources and first and second sensing inputs; a first sensor associated with the electrically released latch and which serves to connect the first data stream source to the first sensing input other than when the latch is in its released state; a second sensor associated with the door and which serves to connect the second data stream source to the second sensing input so long as the door remains closed; and a third sensor also associated with the door and which serves to link together one of the first and second data stream sources and the first and second inputs when the door is not closed; the processing unit being arranged to output a signal indicative of an error condition should the data stream appearing at least at one of the sensing inputs not be the data stream which normally should appear at that input.