# Driver History Tags **URL:** \ **Category:** Module Development\ **Created:** [February 11, 2014, 3:42pm UTC](https://forum.inductiveautomation.com/t/driver-history-tags/7986 "2014-02-11T15:42:25Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![lisawas](https://avatars.discourse-cdn.com/v4/letter/l/4bbf92/32.png) [@lisawas](https://forum.inductiveautomation.com/u/lisawas)\ **Post date:** [February 11, 2014, 3:42pm UTC](https://forum.inductiveautomation.com/t/driver-history-tags/7986/1 "2014-02-11T15:42:25Z")
Got the subscription logic functional for my driver. Via the OPCXML protocol, I can set my driver to either return all subscribed tags when polling a subscription, or just the tags that have changed. When I set the driver to the latter, Ignition seems to flag the unchanged tags as having failed, and they’re marked with a red ‘x’. The ‘x’ goes away when they are later updated. The problem is that when the history for these tags is turned on, they’re making a huge number of records. When I set the driver to return all tags, whether or not they’re updated, they seem to make a record every time they’re polled. Otherwise, they make records when they change AND when they go dead. Is there something special I need to do in my driver to make my tags only log when they’ve changed? ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [February 11, 2014, 3:53pm UTC](https://forum.inductiveautomation.com/t/driver-history-tags/7986/2 "2014-02-11T15:53:23Z")
The server expects subscribed tags to be updated at the sampling rate regardless of whether the value has changed. Eventually, when (sampling rate \* stale threshold) has elapsed without an update, the server marks the tags as stale. Further upstream from you, in the server, there should be a filter in place (on the OPC-UA MonitoredItem) that prevents changes in timestamp alone from being reported to the UA client, unless the UA client has requested a different filter configuration when creating the MonitoredItems. Ignition’s UA client always chooses a filter configuration that results in values being reported upon change in quality or value, but not in timestamp. ---
**Author:** ![lisawas](https://avatars.discourse-cdn.com/v4/letter/l/4bbf92/32.png) [@lisawas](https://forum.inductiveautomation.com/u/lisawas)\ **Post date:** [February 11, 2014, 4:02pm UTC](https://forum.inductiveautomation.com/t/driver-history-tags/7986/3 "2014-02-11T16:02:06Z")
And OPC-UA MonitoredItem is a part of the database driver or configuration? It’s not something that needs to be present in a regular OPC-UA driver? ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [February 11, 2014, 4:14pm UTC](https://forum.inductiveautomation.com/t/driver-history-tags/7986/4 "2014-02-11T16:14:18Z")
It’s not anything a driver implementation needs to worry about, it’s just the background information and the reason why you shouldn’t be seeing duplicate values get logged in SQLTags history. I have a hard time believing the filtering isn’t working, so you’ll have to show me something that indicates otherwise. ---
**Author:** ![lisawas](https://avatars.discourse-cdn.com/v4/letter/l/4bbf92/32.png) [@lisawas](https://forum.inductiveautomation.com/u/lisawas)\ **Post date:** [February 11, 2014, 4:16pm UTC](https://forum.inductiveautomation.com/t/driver-history-tags/7986/5 "2014-02-11T16:16:45Z")
Is it something we can set on our gateway? Some history configuration? ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [February 11, 2014, 4:23pm UTC](https://forum.inductiveautomation.com/t/driver-history-tags/7986/6 "2014-02-11T16:23:28Z")
There’s nothing you should need to set, Ignition’s UA client always uses a filter that requests only changes in status or value be reported when creating monitored items. ---
**Author:** ![lisawas](https://avatars.discourse-cdn.com/v4/letter/l/4bbf92/32.png) [@lisawas](https://forum.inductiveautomation.com/u/lisawas)\ **Post date:** [February 11, 2014, 5:20pm UTC](https://forum.inductiveautomation.com/t/driver-history-tags/7986/7 "2014-02-11T17:20:09Z")
Is there anything that could cause the tag quality to ‘flicker’? I’m updating everything again, and the tags are still logging far in excess of their value changes… ---
**Author:** ![lisawas](https://avatars.discourse-cdn.com/v4/letter/l/4bbf92/32.png) [@lisawas](https://forum.inductiveautomation.com/u/lisawas)\ **Post date:** [February 11, 2014, 5:47pm UTC](https://forum.inductiveautomation.com/t/driver-history-tags/7986/8 "2014-02-11T17:47:58Z")
We moved the tags to a separate scan class and historical scan class, and now they’re behaving as they should…not sure what caused that, but for anyone else, that’s a potential fix.