12 Replies Latest reply on Aug 30, 2016 2:31 AM by Quyet

    Tag value shows Scan off

    Quyet

      Hi,

      Please anyone can help me in my issue. I modify tags to use the new interface OPC but the value shows Scan Off. The Interface configuration is in last image below. It may cause by PI Host Information in interface configuration, the Server is PISVR1, not PISRV1? The correct PI Data Server is PISRV1. Thanks.

        • Re: Tag value shows Scan off
          Steve Boyko

          When you have a Scan Off event (or a Configure event) the best place to look is the PI message log on the computer running the PI interface. Usually there is a message there referencing your tag name that will give a clue about why it is not working.

          I'm going to take a guess and say that the location2 attribute of your tag is causing the problem. Location2 is where you specify the data type handling, to force the PI interface to interpret the data as a certain type of data (float, string, etc.) rather than making its own assumptions. I don't believe 30 is not a valid number to put there; normally it's 0 to 8 or greater than 1024 in very special cases. Typically you would set location2=0 unless that doesn't work, in which case you look at the documentation and go from there.

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          • Re: Tag value shows Scan off
            Quyet

            I tried setting Location2 = 0 but it is still not working. Where is the PI message log on the computer running the PI Interface? I find in C:\Program Files (x86)\PIPC\Interfaces\OPCInt directory but there is no log file on that directory.

            Thanks.

            • Re: Tag value shows Scan off
              Quyet

              Hi,

              Many thanks to Kelsey, the issue with default PI Data Archive name is fixed and I have passed the PI Buffer Subsytem configuration.

              Back to issue of tag "Scan off", it is still not working, I check the log and it says "instrumenttag empty" as below:

              so please show me where I can find the instrument tag? and what is "exdesc" as mentioned in log.

              Many thanks,

              Quyet

                • Re: Tag value shows Scan off
                  Steve Boyko

                  The instrument tag is the connection between PI and the control system. You have to fill the instrument tag field with what the tag is known as in the OPC server.

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                  • Re: Tag value shows Scan off
                    kholstein

                    Hi Quyet,

                     

                    The instrument tag will have different meanings based on the data source. For PI Points coming from the PI Interface for OPC DA, the instrument tag needs to contain the item name on the OPC Server for the measurement you're trying to collect. Please see the Live Library documentation for more info - PI Interface for OPC DA

                     

                    Exdesc is the extended descriptor, which is also used to indicate certain configuration information. For the PI Interface for OPC DA, you can use this field to specify the OPC item ID if it is too long to fit in the instrument tag field. Since your instrument tag was blank, the PI Data Archive also checked the exdesc to see if the item ID was specified there. More info here - PI Interface for OPC DA

                     

                    Note that the OPC item ID is a property of the data source (not the PI System), and thus we cannot always teach you how to acquire it. However, the PI Interface for OPC DA comes with the OPC Client, a tool that lets your browse OPC Servers and their data (if your OPC Server supports browsing like the simulation OPC server we are using in the course's VLE).

                     

                    The Create Float & Digital PI Points Using Point Builder in PI SMT video in the Configuring a Simple PI System online course walks you through how to use the OPC Client to find the OPC item IDs for OPC Servers that support browsing. I recommend you take a look at that for info on obtaining the correct info for the instrument tag field for your OPC PI Points.

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