The limitations of POSIX time...
Andreas and I did a quick test using an ODBC dataset that is linked to an Excel sheet with data prior to 1970.
When we create a trend with this data, all data prior to 1970 is not displayed (and gives an error message). The presentation you attached (from vCampus Live! 2011) states otherwise.
I've contacted the original presenters to find out how they achieved it. I'm sure they will come back to us shortly.
Ok, you guys caught me. I never do this and usually test things before I recommend them to customers. But this time I went out on a limb and it turns out this bit me. Argh! Never again.
That said, we are looking into a few things now:
1) Whether the issue Michael/Andreas found is a bug in PI Processbook.
2) If relational datasets in PI WebParts work correctly with pre-1970 data.
3) PI AF SDK 2.5 (currently in CTP) adds an enhancement to support trending in ProcessBook for AF table data references. We have confirmed this works with future data, and will test to confirm that it also works with pre-1970 data.
Stay tuned for further updates on these items...
FYI. I was messing with this in PB 2012 (not yet released). We currently support dates between 1/1/1970 and 1/1/2038.
Did some digging around, and with the help of the PI ProcessBook PM (Laurie), I came to the conclusion that at this point it is not possible to trend data that is pre 1970 (lower POSIX Time limitation).
Unfortunately there is no way to do this today with ProcessBook, but we are aware of the issues and hopefully address in a future release...
That said, we are planning to publish a KB article on how to access pre-1970 data in Excel (hint: Get External Data) and mash it up with data from PI DataLink.
Is there any interest in visualizing this data in PI WebParts or PI Coresight? If so, we can look into if/how this is possible.
E-mail from Laurie (note that PITimeServer is a shared library used by PI SDK and AF SDK, including PI Clients and PI Data Access products):
Actually, the root of the problem is the POSIX time model implemented in the PITimeServer. The complication is the PI Clients' dependency on the PITimeServer as it exists in the PI SDK today.
Sorry for getting your hopes up. I guess we need to look into this further at some point...
Is there a possibility to visualize data prior to 1970 in PI WebParts? I guess it would not be using displays generated in PI ProcessBook
It's another possibility that we are considering using
As long as you are happy with a table - yes. But the trend webpart shows the same behavior - invalid time.
Retrieving data ...