| 摘要 |
PROBLEM TO BE SOLVED: To prevent chattering. SOLUTION: A liquid level to be detected is taken as a set value. When the reading of the liquid level in a bulk storage tank is below the set value and no transmission record exists, a contact signal is transmitted at lest once and this signal transmission is recorded and maintained until reset. A transmission record erasure level is a liquid level spaced more apart from the set value than a liquid surface swing width in the bulk assumed therefrom so that it can be determined to be not an error. When a reading exceeds the transmission record erasure level, the transmission record is reset. When a reading for the liquid surface reaches the set value, a contact signal is transmitted at a predetermined frequency, so that, even when the liquid surface swings, no chattering such as interruption of the liquid surface signal occurs. Also, once the liquid level reaches the set value, the transmission record is not miserased.
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