7 Replies Latest reply on Aug 8, 2018 2:23 AM by pocholo.mendoza

    PI OPC Tag timestamp mismatch

    pocholo.mendoza

      Hello everyone,

       

      I'm not sure if this issue has already been discussed in past threads, but this issue has been haunting us for a while. We are encountering an issue wherein the timestamps of the tags from the PI Server do not match the timestamps from the OPC Server. We've already established a time sync with the PI Server machine with the OPC Server. During our tests from the PI OPC client tool, the data archive and PI Vision, some values and timestamps match, but most of the time they don't.

       

      We're sure that we've set the interface to follow the timestamp of the OPC. Below are screenshots of our configurations:

       

       

      As you could see here original timestamps have been set.

       

      I've seen in the documentation that there is a parameter you set as well in the startup? (i'm assuming cmd?) wherein if you would want to set the interface to follow the timestamp from the OPC Server you set it as "/TS=Y" Where do I set this?

       

      Thank you!

       

      Best Regards,

       

      Cholo

        • Re: PI OPC Tag timestamp mismatch
          Lal_Babu_Shaik

          Hi Pocholo

           

          Request you to check below KB article on /TS parameter

           

          https://techsupport.osisoft.com/Troubleshooting/KB/KB00305

           

          Could you please let us know your PI server timezone ? Believe your OPC server is in UTC.

           

          Thanks

          Lal Babu Shaik

          1 of 1 people found this helpful
            • Re: PI OPC Tag timestamp mismatch
              pocholo.mendoza

              Hi Shaik,

               

              Thank you for the link. I've seen this documentation before, but it does not specify where I would set the /TS parameter for startup. I'm not sure if this is a command that should be executed in the command line?

               

              Thank you!

               

              Best Regards,

               

              Cholo

                • Re: PI OPC Tag timestamp mismatch
                  Lal_Babu_Shaik

                  Hi Pocholo

                   

                  Request you to check %pihome%interfaces --> yourinterface.bat file for this parameter.

                   

                  Thanks,

                  Lal

                  1 of 1 people found this helpful
                  • Re: PI OPC Tag timestamp mismatch
                    jyi

                    Hi Cholo,

                     

                    Here is a little explanation to /TS Parameter. The /TS parameter is displayed in UI as your second screenshot. I'm sorry if our manual was little misleading. Let me help you do the matchings:

                    It's the same whether you modify /TS parameter in the batch file or change the setting in the UI.

                    By the way, if you mouseover to each radio buttons from PI-ICU, it tells you what command line parameters the UI indicates.

                     

                    Timestamps

                    • Original Timestamps                                      => /TS=U
                    • Original Timestamps adjusted to PI Server   => /TS=Y
                    • Original Timestamps for Advise Tags Only   => /TS=A
                    • PI Server provides All Timestamp                => /TS=N

                     

                    The description for each one is probably better served in the manual or KB00305.

                    1 of 1 people found this helpful
                      • Re: PI OPC Tag timestamp mismatch
                        pocholo.mendoza

                        Hi Jinmo,

                         

                        Thank you for your response!

                         

                        I've also noticed in article KB00305 that there was an example where the OPC Server, PI Interface and PI Server were all using different time zones which explains different timestamps but with the same data.

                         

                        But in our case, what if all three were using the same time? Our setup is that our PI OPC Interface is in the OPC Server and is connected to our PI System. We've already established time syncs with all three, from our understanding the data we should be getting from the OPC is the same with the same timestamp as well. We get the same data and timestamp sometimes, but most of the time data and timestamps are not the same. There are some cases where we compare the data from the OPC and from what the PI Server has received at a certain time and they seem not to much.

                         

                        Would you have any idea why this is happening? And do you have any solutions in solving this? Or am I just not getting how the interface fully functions?

                         

                        Thank you!

                         

                        Best Regards,

                         

                        Cholo

                          • Re: PI OPC Tag timestamp mismatch
                            jyi

                            How much of a time difference do you see between your OPC Server clients and from PI System? For a detailed answer, it would be better for you to call our support lines or open a case.

                             

                            But usually, there is always a minor deviation between multiple nodes so that PI Interface takes care of these minor deviation via /TS parameters. This is true even if the time zones are all the same.

                            Even if all computers are synced with one time-source, between syncs there will always be some minor time differences.

                             

                            KB00305 also tells this part of the story by making differences in the minutes. Please note that the machines are all in the different time zones but also with different minutes.

                            Time zone differences usually go by hours(in some cases 1/2 hour) but their minutes should be the same. In real life, this is not the case. This is where offsets come in to mitigate the time differences in two different machines.

                            The following part of manual explains about the Time stamp options in PI-ICU and the offsets applied to the original timestamp.

                              • Re: PI OPC Tag timestamp mismatch
                                pocholo.mendoza

                                I think it wouldn't be necessary to open a case for this. I just want to get a clear explanation of what I might be missing from my understanding with this interface.

                                 

                                From my understanding, you're saying that despite syncing all machines with the same time and ticking the timestamp parameter with "original timestamps" which is equivalent to "t/s = u", there is still a possibility of a deviation with the data and timestamp? I think offsets are not necessary as well since my setting for the ts/s parameter is set to original timestamp and specified that it does not apply any offset to the time stamps.

                                 

                                 

                                Thank you!

                                 

                                Regards