2 Replies Latest reply on May 19, 2017 6:35 AM by Muthulingam

    PI 'digitalset' Attribute - PI Alarm Tag Status seems to be in reverse order when compared to DCS Alarm Tag Status


      Dear friends,

      I noticed a lot of PI Alarm Tags Status (Inherited/ Historical Tags from Previous Platform Operator) seems to be in "reverse order" when compared to the actual DCS Alarm Tag Status.

      The previous PI Programmer asked me to just flip the 'digitalset' Attribute from "NormalTRIP" to "TRIPNormal" and check if the Value is 'True' (i.e. matches the Value in DCS), if yes then it is safe to flip the 'digitalset' Atrribute setting for all the Alarm and Status Tags that are affected.


      For example, all the PI Tags below are showing a Reverse Alarm Status when compared to the actual DCS Alarm Status:



      Is there another approach to check and rectify the above condition, or is the above method the best approach?

        • Re: PI 'digitalset' Attribute - PI Alarm Tag Status seems to be in reverse order when compared to DCS Alarm Tag Status

          Hi Muthulingam,


          I think we need to determine where the issue is. Is it the misconfiguration of the digital set as you have mentioned, or is it because the values are not up to date in the PI System.


          First thing to do is to confirm that the timestamps of the alarms/values matches that of the DCS, only that the statuses are in reversed order, eg. the PI Point value for 26PN-120CB turned NORMAL at 10:21:01 AM 19-May-2017, but in DCS the asset actually went into a TRIP state at that exact time. In this case, we know that the digital state for that tag is misconfigured such that the order is reversed. In this case, you will need to change the digital state to reflect the correct status of the tag. You will need to be careful when changing the digital state set to ensure all tags using this digital state set all have the same behaviour, eg. 0 = NORMAL and 1=TRIP. If only some tags are of reversed order then you should create a new digital state and reconfigure those tags to use the new state set (usually this should not be the case but it's better to confirm instead of assume).


          However, if you find the timestamps of the tags does not match that of what is happening in the DCS, then further investigation needs to be done to determine why the PI Points are not in sync.


          Hope this helps.

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