# System.opc vs system.tag

**URL:** <https://forum.inductiveautomation.com/t/system-opc-vs-system-tag/6231>\
**Category:** Ignition\
**Created:** [April 15, 2013, 3:40pm UTC](https://forum.inductiveautomation.com/t/system-opc-vs-system-tag/6231 "2013-04-15T15:40:20Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![m.digon](https://avatars.discourse-cdn.com/v4/letter/m/41988e/32.png) [@m.digon](https://forum.inductiveautomation.com/u/m.digon)\
**Post date:** [April 15, 2013, 3:40pm UTC](https://forum.inductiveautomation.com/t/system-opc-vs-system-tag/6231/1 "2013-04-15T15:40:20Z")

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Hello all!

I have a doubt about the main difference between system.opc and system.tag. What reading is faster?

Thanks for your help! ![:thumb_left:](https://us1.discourse-cdn.com/inductiveautomation/original/1X/e26afb081ddde6df016df6ee49159cf56aaca688.gif ":thumb\_left:")

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**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:** [April 15, 2013, 3:43pm UTC](https://forum.inductiveautomation.com/t/system-opc-vs-system-tag/6231/2 "2013-04-15T15:43:00Z")

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system.tag.read\* is faster because it will just read the current value of the SQLTag. system.opc.read\* has to make a trip to the OPC server and back.