Let’s say I have 2 tags val1 and val2, both initiated with value of 5. val1 changes value at 00:00 and again at 00:10, then val2 changes value at 00:20. I will then have this table at Database:
|time_stamp | val1 | val2|
|00:00 |5 |5 |
|00:10 |9 |5 |
|00:20 |9 |9 |
What kind of transaction group, and set up, should I use to have below table instead?
|time_stamp | val_index | value|
|00:00 |1 |5 |
|00:00 |2 |5 |
|00:10 |1 |9 |
|00:20 |2 |9 |
Use the regular tag historian instead of a transaction group. The tag historian uses “tall” format with tag IDs.
Thanks pturmel for the response. Transaction Group also offer feature to log multiple tags on value change of 1 (or more) tag. As far as i understand, Historian can only log tag based on its value change. Is there any work around to Historian based on other tag value change?
Your example of “tall” shows only one value being recorded for the latter changes. That is what the tag historian will do. A SQL Bridge transaction group logs multiple values together with a single timestamp. The two approaches are fundamentally different. Use each where you need them.