3 Replies Latest reply on Jun 15, 2016 3:55 AM by John Messinger

    PI Digital States - Documentation or Explanation

    calmandrysdale

      Hello,

       

      I have been reading the PI Server System Management Guide around the PI Digital States.

       

      I am a little confused as the guide jumps straight into setting them up and configuring them but doesnt cover much around the concepts or purpose of them.

       

      Primarily I am interested in the System digital set. It seems that there are a number of predefined items; or that you can map an interface to define a certain number of items.

       

      I guess I am looking for some clarity around the following:

       

      * What is the purpose of the System digital set?

      * Are you supposed to map interfaces to have items within the system digital set or add a new set?

      * Is there any way of telling which interfaces are mapped to which items?

      * Is there any further documentation which discusses this further?

       

      Any pointers very much appreciated. I feel like I have either misunderstood the intent of the System digital set or how the interfaces are related to it.

       

      Thanks

       

      Calman

        • Re: PI Digital States - Documentation or Explanation
          John Messinger

          Hi Calman,

           

          The System digital state set is intended to provide system wide 'error states'. Digital tags are usually configured to reference their own state sets which provide the 'normal' values for these tags. As you know, many digital tags can reference the same state set, but a digital tag can only reference one digital set. It's not standard practice to map a digital tag for any interface to the System state set. Some interfaces however, may require specific states to be added to the System state set to provide a specific set of error states that may be received from the data source. Other interfaces (like the RDBMS interface for example) have configuration options that allow you to specify a range within the System digital state set for error codes that can be written to the interface tags. System digital states are also written to analogue tags as error states, such as 'I/O Timeout' or 'Intf Shut' etc.

          In answer to your other questions, there is no easy way to tell which interfaces (or more specifically, their tags) are mapped to which digital sets. You could do an advanced tag search where you specify the point type as digital, and the digitalset attribute equal to a specific state set name. Alternatively, just search for all digital tags in PI Builder, and then sort the returned list by the digitalset attribute. Otherwise, there is really nothing that exposes a mapping between digital tags and digital state sets. As for documentation, the System Management Guide is probably the best source of information, as well as the online documentation here.

           

          Hope this helps.

           

          John

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