| 摘要 |
PURPOSE:To improve dependability of function checking, by switching an analogue switch to the reference voltage source side and performing an operation check of an A/D convertor. CONSTITUTION:A micro-processor PU5 switches an analogue switch 2 into the other contact point 22 to operate an A/D convertor 3. By this arrangement, the reference voltage from the reference voltage source 4 is read into the PU5 through the convertor 3. On the PU5 an input signal and a set range are compared and if the signal is within a set range, the function of the convertor 3 is identified as normal and if not, the function of the convertor 3 is identified as abnormal and an error is indicated on a display 6. Thus, checking of the convertor 3 is available independently of a load-cell 1 for it functioning. Further, by switching of the switch 2, an abnormality of the cell 1 can be identified.
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