| 摘要 |
An indicating electronic timer useful for timing processing events and for controlling a process measures the elapsed time from a moment at which a process variable attains a predetermined value and produces a signal which varies in accordance with the elapsed time. During a timing operation, the signal is displayed on a display device which normally displays the process variable, and may be such that the display device indicates the percentage of a predetermined time interval which has elapsed. The timer may be conveniently implemented with relatively inexpensive integrated circuits, such as a variable oscillator, binary counters, and D/A converters.
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