Historian not logging initial value

Ignition
1

I started logging history of a bunch of tag. I notice that the table sqlth_te doesn’t contain all of my tag. they seem to be added to the table only once they changed.

Is this the way it should work?
I feel like it should be logging at least an initial value once you enable the history.

When i try to show these value on an easy chart it seems like the history wasn’t start until the tag changed it make weird graph.

Is there a way to force it to log an initial value as soon as you enable history on a tag?

2

By default the tag historian only records values when they change so the behaviour you’re seeing is normal.

The “Max Time Between Records” option allows you to change how many times the scan class is executed before it’ll write the value to the database, even if the value has not changed - be careful though as that could lead to a pretty hefty database size. You could use this to get what you want? It’s probably not the most elegant solution though.

1 Like