We've developed a tool that pulls updates from any tag on the PI server and we store all of the pi tag attributes in a csv file. We noticed one instance where the changedate value included "timeweighted". How would "timeweighted" appear in the pi tag attributes?
@Tim: AFAIK, there is no timeweighted attribute but a CalcMode attribute of a totalizer point (derived from a totalizer point class) can have 'timeweighted' as value. I imagine this is what the tool is reporting about.
This is the value of attribute and not the attribute name itself.
Thanks Mathieu, so the Changedate value actually contained a value of "timeweighted, 7/22/2013 4:25:51 PM". Our expected changedate value was only 7/22/2013 4:25:51 PM. What would cause the 'timeweighted' to appear?
@Tim: I couldn't think of something different than a configuration change on that PI Point. Can you get the value of the changer attribute, this should tell you would made the change if different from the last time.
Is the ptsecurity attribute is defined correctly to allow only administrators to change the configuration?
Points can belong to different Point classes and different point classes have different point attributes.
Tags that are serviced by the PI Totalizer subsystem are member of the "Totalizer" point class which has an attribute "CalcMode" that I believe is unique for "Totalizer" point class - at least with the default point classes.
When retrieving the configuration of "Totalizer" tags using PI SMT add-in for Microsoft Excel, I see "CalcMode" on the left hand side besides "changedate" attribute.
Is it possible the information within "CalcMode" has been merged into "changedate" within your application?
Because all point classes use the attributes from "Base" class plus additional ones, I suggest storing configuration data separated by point classes within your application - if this makes sense to you.
What's the purpose of your application? Are you auditing the point table?
If you could please attach a spreadsheet generated using PI Tag Configurator, which is an add-in of Excel, with the configuration of this specific tag, we might be able to help you better.
If you don´t know how to do that, please let us know and we will help you!
small problem with that is that i cant reproduce this scenario. one of our customers found this issue. I just would like to know some possibilities where "Timewheighted" would appear in the changedate attribute of a tag. From the discussion thus far it seems like it could be stemming from a Totalizator point class.
What is the purpose of the Totalizer point class, what would be a scenario where someone would use this class?
I can only assume that your "tuning" application changes tag attributes used by Exception and Compression. I understand the motivation for the attempt to make a PI system managers life easier. However to apply good Exception and Compression settings it's not only necessary to have a good understanding how Exception and Compression works. Rather one also needs a good understanding of the process data and about the "interface" collecting the data and servicing tags in PI. This said, I wouldn't trust into any kind of automation but prefer maintaining settings manually. This doesn't imply to find a good setting for each individual tag or that each individual tag needs to be set up manually.
Based on data types and value ranges, basic settings can be suggested that will deliver good results in the majority of cases and make a fine tuning necessary only for a smaller percentage of tags only i.e. those supposed to record pretty busy signals. I consider reviewing recorded data a necessary requirement. Asking the "data users" for their opinion is a good practice. Signals that require changes can usually be grouped, so settings need to be evaluated for a smaller subset of tags only and could than be applied for others of the same kind. PI SMT Tag Builder add-in for Microsoft Excel is my preferred tool for this kind of work.
PI Totalizer Subsystem is a calculation engine belonging to the so called PI Server applications. Because of the specific configuration requirements (additional attributes) of PI Totalizer Subsystem all belonging tags are using "Totalizer" point class. I recommend not treating tags with pointclass = "Totalizer" with your "tuning" application since this may have a direct impact on calculation results. PI Totalizer may report status "Configure", "Bad Sample" or similar because of the changed configuration until the next reset (clock scheduled or event triggered) occurs.
Hi Rhys, not a problem! I think I've got the answer to my question and have forwarded the issue over to our developers to be fixed. If you'd like to know more about our product you can visit our website and download a free trial of CompressionInsight. You can also contact me at tim.read@patterndiscovery.com.
Again, thanks to all who helped with this question. I for one have learned something new (yet again) about the OSI PI system.