Importance

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Abstract

An electrical instrumentation system comprises plural sensors that provide data signals representing values of parameters of interest to a CPU that in turn presents corresponding signals in multi-bit forms to corresponding indicator gauges. Each indicator gauge comprises a latching memory circuit in which the multi-bit data received from the CPU is latched, a free-running counting circuit, and a comparator circuit that compares the counting of the free-running counting circuit to the data in the latching memory circuit. The counter repeatedly counts from an initial to a final value, and when the comparator detects coincidence of the count to the latched data during each such counting interval, it switches the state of a bi-stable circuit. The bi-stable circuit assumes one state during the portion of each counting interval preceding the coincidence detection, and the other state during the portion of each interval succeeding the coincidence detection. The bi-stable circuit produces a pulse width modulation of the electromechanical movement of the gauge to cause the gauge to indicate the value of the latched data, and hence, the value of the corresponding parameter. Each gauge does not require the continuous attendance of the CPU thereby freeing the CPU to perform other tasks during times that it is not updating the latched data in the gauge.

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First Claim