Historical DeadBand not applied


i’m facing troubles with tag historian. I want to use the deadband functionality that should register a change any time the value moves +/- the specified amount from the last stored value (in discrete mode).
Instead it’s register at any 10 second (my scanclass) even if the value has not changed.

What i’m doing wrong? Or maybe my expecations are wrong, so maybe somebody please can give an description of how deadband field works?
I tryed in many differend way but the result is always the same: the deadband field is ignored and the value is stored with frequency defined in scanclass.

Thanks for your kind feedback.

Hi Igor,

Have you set your max time between records to unlimited? This is taken from the manual:

Max Time Between Records
Normally Tag Historian only stores records when values change. By default, an “unlimited” amount of time can pass between records – if the value doesn’t change, a new row is never inserted in the database. By modifying this setting, it is possible to specify the maximum number of scan class execution cycles that can occur before a value is recorded. Setting the value to 1, for example, would cause the tag value to be inserted each execution, even if it has not changed. Given the amount of extra data in the database that this would lead to, it’s important to only change this property when necessary.

Hi Jonathan,

yes, max time between records is set to unlimited.