9 Replies Latest reply on Jan 11, 2017 8:21 AM by mtamane

    Clearing Datalink Cache


      I have been experiencing issue with the Datalink cache.


      When i try to pull current value from PI Datalink using PI AF Element, it shows "PI Point not found '\\server\tagname1345.DOR'."

      I have check the from PI System Explorer and it shows correct, the value shows "Pt Created". I am suspecting there's an issue on the PI Datalink cache, so i clear the cache from the PI Datalink setting, but the issue remain.


      Do you guys ever experience similar issue?

        • Re: Clearing Datalink Cache

          I have tried to reproduce the issue, but it worked without problems in my environment.


          Did you enable auto refresh?

          When you query for an AF attribute that refers a non-existent PI tag, and then create that PI tag, DataLink does not retrieve values unless auto refresh is enabled or refresh manually.

          If refreshing the sheet does not work, then please try restarting Excel and querying current value again.


          Please let me know if you have any questions.

            • Re: Clearing Datalink Cache

              I have restarted the excel, but its still the same. The issue happen yesterday, so i have already let it overnight and run the excel again this morning.


              I did the refresh with F9..

                • Re: Clearing Datalink Cache

                  For that case, the root cause could be following:


                  1. The tag does not exist on PI Data Archive server
                  Please make sure the tag exist on the PI Data Archive server by using PI System Management Tools.
                  Also, please check the current value of the tag as well.


                  2. The user account does not have read access to the tag
                  Please make sure the user account opening Excel has read access to the PI tag.
                  You can check tag security by opening PI System Management Tools > Points > Point Builder.


                  If the user account does not have read access to the tag, then the user cannot see the tag.
                  This means that the message "PI Point not found" is shown to the user.
                  If the user accounts that open PI System Explorer and Excel are different, then it should be why the issue occurred.

                    • Re: Clearing Datalink Cache

                      Hi Motoki thanks for the suggestion but :


                      1.  The tags does exist in PI Data Archive. I have check manually at PI SMT, and manually browse from PI System Explorer. The value shows Pt Created.


                      2. The user does have access to the tag. i have granted piadmin access to the user, and the user is the owner/creator of the PI AF Database.


                      I do believe its Datalink cache issue. I run the Datalink function again this morning, it finally shows the value. Probably it takes two days to clear the cache.

                        • Re: Clearing Datalink Cache

                          Which version of PI DataLink are you using?


                          Steve Kwan

                            • Re: Clearing Datalink Cache

                              Im using PI Datalink 2016 Version 5.3

                                • Re: Clearing Datalink Cache

                                  PI DataLink checks last update date of the cache and refreshes if cache is older than 6 months.
                                  Also, pressing Clear cache button and/or restarting Excel should clear cache.


                                  I am not sure why it took 2 days to show the correct result, but if you see this problem again, please try to disable caching.
                                  In order to do this, edit AFSDK.config located in the %programdata%\OSIsoft\AF\ directory.
                                  When you open AFSDK.config by using notepad or any text editing softwares, you will see following line:
                                    <Cache maxObjects="10000" time="120" />
                                  Change the parameter maxObjects to 0, restart Excel, open a new spread sheet and try querying new current value.

                                    • Re: Clearing Datalink Cache

                                      i already did this. i have read it somewhere from pisquare. i have change the maxObjects="0" . This was few days ago.


                                      Btw, today i query again, and its shows the same error again.

                                        • Re: Clearing Datalink Cache

                                          Did you query the same AF attribute and got the same error?
                                          Then it might be the other reason than cache problem.


                                          Could you try querying the current value for the PI point shown in the error message from PI Data Archive (not AF attribute)?
                                          Also, could you try querying for the other AF attributes with timestamp in order to see whether this issue is caused in the other attributes?