AnsweredAssumed Answered

bad interval filtering

Question asked by Saken on Oct 28, 2019
Latest reply on Oct 29, 2019 by Raja3206


we have tag where we need to filter interval with bad data, tag has allowable limit, let's say from 170 and 127,

below is bad interval starts from 114 and ends with 170.27:

I was trying to use StDev, StDev for 170 and 127 is about 8,7 now I'm not sure how to apply it to identify bad interval.

For bad interval I tried to use something like StDev('attr', '-2m','*') to calculate deviation between last value and previous value (then compare with allowable limit StDev) but it doesn't work, another issue with this is how to handle deviation when last and previous value is equal. 

The reason I was thinking about StDev for bad interval, when evaluate it correctly set big deviation for end interval 170.27 so puts it inside the filter and put 172.59 outside the filter since less deviation between 170.2 and 172.59 but it doesn't work when try to output to tag, gives completely different deviation.