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Abstract

A time slot interchange switch matrix incorporates processor-controlled diagnostic functions to provide programmable on-line/off-line diagnostic monitoring. The switch matrix output can be tri-stated during program-selected time slots while remaining electrically connected to the PCM buses, allowing redundant switch matrices to share on-line time slot interchange switching in any programmable manner. Inject and monitor circuitry enables the switching function of the on-line switch matrix to be tested time slot by time slot under program control using unused time slots. Parity checking, including verification of check circuitry, is provided for input PCM data, control memory addressing output, and data memory output through the tri-state output drivers. In addition to on-line inject and monitor testing, the off-line switch matrix selectively monitors the output of the on-line matrix to confirm that it is driving the PCM buses. If a malfunction is detected, the faulty switch matrix may be electrically disconnected from PCM buses by remote command.

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First Claim