Bad values in tag history

Ignition
1

Hi!
Sometimes I have bad values stores in MySQL and I don’t know how I got it…
screenshot.su/show.php?img=4c4b5 … 4cbd8c.jpg

  1. How can I know why it happens?
  2. How to delete this bad values from tag history?
  3. How to limit records if I got values like this?
2

What’s bad about them? They are very close to zero, but otherwise valid floating point values.

3

The can’t be so low or so high…
Should be from 0 to 10000.

4

Floating point values can have round-off issues – unavoidably. The number you circled is -0.0000000006959. That’s zero for most purposes. Add deliberate rounding (in the PLC, probably) to the appropriate number of decimal places if that’s a problem.

5

But how to delete these values?