摘要 |
An interlocking system comprising a plurality, e.g., three, of parallel sub-systems operating asynchronously to produce identical replicated outputs which are mutually compared to determine the correct output and disqualifying a minority output thereby ensuring high system integrity. Each sub-system includes a similar arrangement for computing the difference between all possible pairs of sub-systems. Comparison of these results with a reference table of all possible difference results and then comparison of the difference equations yields a common factor which is the sub-system producing the error. Action can then be taken to disqualify its output, e.g., by switching-off its power supply. A final output is taken, preferably from one sub-system, with a second as standby. To accomodate asynchronous running, a final output is only acted upon if it is repeated in a succeeding output cycle thus permitting opportunity to disqualify the preferred output if it is judged in error by the other sub-systems and to replace it by the standby.
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