| 摘要 |
The invention relates to a two-wire transducer in automation engineering that outputs a measurement signal as an injected current. For the method to test the serviceability, it is proposed to increase the DC loop current (I<SUB>S</SUB>), independently of the measured value, from the minimum value towards the maximum value (I<SUB>SM</SUB>), and to measure the input voltage (U<SUB>E</SUB>) across the internal resistance of the transducer in the process, and to compare it with a definable threshold value (U<SUB>ES</SUB>) that is greater than the minimum input voltage (U<SUB>EM</SUB>) required to maintain serviceability. If the input voltage (U<SUB>E</SUB>) falls below the threshold value (U<SUB>ES</SUB>) before the DC loop current (I<SUB>S</SUB>) has reached its maximum value (I<SUB>SM</SUB>), the DC loop current (I<SUB>S</SUB>) is reduced until the input voltage (U<SUB>E</SUB>) reaches at least the definable threshold value (U<SUB>ES</SUB>), and the error is signaled.
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