# Historian Scan class or other

**URL:** <https://forum.inductiveautomation.com/t/historian-scan-class-or-other/4451>\
**Category:** Ignition\
**Created:** [May 11, 2012, 4:43pm UTC](https://forum.inductiveautomation.com/t/historian-scan-class-or-other/4451 "2012-05-11T16:43:22Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![ecujak](https://avatars.discourse-cdn.com/v4/letter/e/839c29/32.png) [@ecujak](https://forum.inductiveautomation.com/u/ecujak)\
**Post date:** [May 11, 2012, 4:43pm UTC](https://forum.inductiveautomation.com/t/historian-scan-class-or-other/4451/1 "2012-05-11T16:43:22Z")

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I have set my slow point to 900,000ms and my stale is double that time. I was hoping that this would only check and store to the DB every 15 minutes. What I am seeing is that there are still records being stored every second for the tag this historian is monitoring.

How do I only scan/store PLC data every 15 minutes.

Please help.

* * *

Version  
License  
Ignition Platform  
7.4.2 (b953)

SQL Bridge Module  
5.4.1 (b160)  
Activated  
Vision Module  
6.4.1 (b505)  
Activated  
Mobile Module  
1.4.0 (b111)  
Trial  
ActiveX Module  
2.4.0 (b93)  
Free  
Symbol Factory Module  
2.6.0 (b35)  
Activated  
Reporting Module  
1.4.0 (b102)  
Activated  
Connected Gateway: : [http://Edit:8088/main](http://Edit:8088/main)  
Java Version: Sun Microsystems Inc. 1.6.0\_29  
JVM Memory (used/max MB): 70.6 / 494.9  
Client Time Zone: America/New\_York [GMT-5:00]  
Gateway Time Zone: America/New\_York [GMT-5:00]

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<div class="post-metadata">

**Author:** ![Colby.Clegg](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/colby.clegg/32/3282_2.png) [@Colby.Clegg](https://forum.inductiveautomation.com/u/Colby.Clegg)\
**Post date:** [May 11, 2012, 5:17pm UTC](https://forum.inductiveautomation.com/t/historian-scan-class-or-other/4451/2 "2012-05-11T17:17:52Z")

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It sounds like you should have it about right. You’re using a direct scan class, right?

1. Create/set scan class, mode=direct, slow rate=900000 (stale time doesn’t matter much for internal tags)
2. Set the tag’s historical scan class to be that SC. The normal scan class can be something faster.
3. Go to Status\>SQLTags in the gateway and look at the scan class. You should see its rate reported at “15 min”, and you should see the tag in the Historical Tag count.

Side note: In your system stats, I see you’re running Java update 29. This version had a big problem that affected JDBC connections. You should upgrade to u31 (they skipped 30) when you get a chance. Doesn’t have anything to do with what we’re talking about, but wanted to point it out.

Regards,