Historical Deadband not working properly

I am using UDT and have memory tag of data type float, and I did the below setting for history to be stored in Mysql database.

However when I change the value from 0 to 1 and from 1 to 2 and from 2 to 3 and from 3 to 5, only 1 gets stored in the database.

When I set deadband to 0 and change value all the change in value gets stored in the database, I dont understand whats going on after I put some deadband.

Ignition uses compression on the historian to reduce data storage requirements. The two main settings that affect this are Deadband Style and Historical Deadband. This is explained in the manual.


Note particularly,

The setting will automatically pick either Analog or Discrete, based on the data type of the tag.

  • If the data type of the tag is set to a float or double, then Auto will use the Analog Style.
  • If the data type of the tag is any other type, then the Discrete style will be used.

You might find Discreet more easy to work with.

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I was having the thoughts that deadband is working like

abs(current value - previous value) >= deadband ---> store

Read the manual carefully. It took me several readings before I grasped how it worked (and even now I'm not sure). I think they have improved the explanation in the 8.1 manual in the link I gave you.

It's much more complex than that for "analog".