Hello,

I have created a dataset containing the sum of two tags and put it into a trend. This causes me no problems untill I change the time range to more than 17 days. When I set the time range for more than 17 days the trace dissapears and the value shows no data. I have tried to trend them separately, and then it seems to work perfectly. Does anyone have a solution for this?

I can add that i have tried to trend the dataset by VBA and define the time range in the code, this does not help.

Thank you in Advance

Hi Sivert,

Thanks for posting on PI Square.

Unfortunately, you ran into a limitation of using Datasets. There is a set amount of memory Processbook has for dataset calculations. Essentially, Processbook has to hold all the results of the Datasets in memory until the calculations are done. Once the calculations are done, Processbook will then render your trend.

If the calculations fail to complete due to Data Timeouts or being Out of Memory, Processbook would fail to render your traces and the results will show no Data.

The time range limitation is based on the complexity of your Dataset.

Workarounds/Recommended Solution:That being said, Datasets are actually the least recommended method of trending calculations. In general, the preferred method (especially when you are trending large time ranges) is to use PI AF Analytics to write calculation results to a PI Tag. That way you are historizing the calculation which makes data retrieval faster and more performance.

For more information of Analytics:

PI Server - Asset Analytics

Other methods include using a Analysis Data Reference (similar to the above solution except not historizing the calculation) or use PI Performance Equation Tags

~Jesse