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How to detect if a TAG was modified in the past and to collect the timestamp of the modified value

Question asked by Lausecker on Aug 28, 2018
Latest reply on Aug 28, 2018 by fwalsh

Dear All,


We would like to be able to detect if a TAG has been modified in the past (modification / addition / suppression of a value within the whole lifetime of the TAG) and to store the timestamp of the modified value.
For example, this could be done through the creation of a second TAG which would be updated at each modification with the current timestamp and with a value which would be the timestamp of the modified data.


The concrete case would be to detect if a value (manual entry) is put into a TAG whatever the timestamp specified for this entry, and to collect this timestamp and store it.


Let me know if you have hints about how to implement this detection in PI. I saw several topics about similar needs but couldn't find something related to this exact need,


Thank you very much,
Best Regards,