I have been following PI Datalink, looking to count how many times an alarm activated and Count tag Entries over a timeframe and to count frequency of entries.
I only need the count, therefore I'm using the calculated data method, however the two answers used slightly different filter expressions:
1. The following expressions give me different numbers and I do not understand what the role of '*' is in the expression:
- TagVal('Tag', '*') > 30 returns 831
- TagVal('Tag') > 30 returns 564
- 'Tag' > 30 returns 564
2. If I have an array of 100 tags, can I use 1 set of calculated data like this? Unsure of whether the expressions would correspond to each data item.
Alternatively I would need to set up 1 calculated data array for each tag?