# system.tag.writeSynchronous in Ignition 8

**URL:** <https://forum.inductiveautomation.com/t/system-tag-writesynchronous-in-ignition-8/24578>\
**Category:** Ignition\
**Tags:** ignition79, ignition80\
**Created:** [May 2, 2019, 1:22am UTC](https://forum.inductiveautomation.com/t/system-tag-writesynchronous-in-ignition-8/24578 "2019-05-02T01:22:19Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![aaron1](https://avatars.discourse-cdn.com/v4/letter/a/b5a626/32.png) [@aaron1](https://forum.inductiveautomation.com/u/aaron1)\
**Post date:** [May 2, 2019, 1:22am UTC](https://forum.inductiveautomation.com/t/system-tag-writesynchronous-in-ignition-8/24578/1 "2019-05-02T01:22:19Z")

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Hi everyone,

We have just upgraded a project from Ignition 7.9.10 to Ignition 8.

In the project we have a lot of scripts that use the **system.tag.writeSynchronous** function to write to tags.

After testing using Ignition 8 it looks like the **system.tag.writeSynchronous** and **system.tag.write** functions still works even though they are no longer listed in the Ignition user manual for version 8. The only thing we had to change was changing the timeout unit from seconds to miliseconds.

My question is can we keep on using **system.tag.writeSynchronous** function in the scripts? (it will be great if we can keep on using it) or is **system.tag.writeSynchronous** and **system.tag.write** going to be completely phased out at some stage in newer versions? And if it’s not recommended to keep on using these two functions then which of the new tag write function should we change to? As I see in the Ignition 8 manual the **system.tag.writeAsync** function seems to be quite different?

Many thanks.

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**Author:** ![PRAMANJ](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pramanj/32/66935_2.png) [@PRAMANJ](https://forum.inductiveautomation.com/u/PRAMANJ)\
**Post date:** [May 2, 2019, 4:08am UTC](https://forum.inductiveautomation.com/t/system-tag-writesynchronous-in-ignition-8/24578/2 "2019-05-02T04:08:13Z")

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I had asked a similar question whether synchronous read and write will be deprecated in version 8 or not. I was told that they will internally use the asynchronous calls but they will continue to be supported for backward compatibility so that existing code of many users will not break. However they are not documented so that people use the async versions. Someone from IA may confirm please. Also please confirm if it will have an impact on the performance (using sync vs async in new versions of Ignition).

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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:** [May 2, 2019, 1:19pm UTC](https://forum.inductiveautomation.com/t/system-tag-writesynchronous-in-ignition-8/24578/3 "2019-05-02T13:19:53Z")

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They won’t stop working.

`writeSynchronous` has been replaced by `writeBlocking`.

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**Author:** ![besaliealprince](https://avatars.discourse-cdn.com/v4/letter/b/0ea827/32.png) [@besaliealprince](https://forum.inductiveautomation.com/u/besaliealprince)\
**Post date:** [December 9, 2021, 4:52pm UTC](https://forum.inductiveautomation.com/t/system-tag-writesynchronous-in-ignition-8/24578/4 "2021-12-09T16:52:53Z")

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> [@Kevin.Herron](#):
>
> writeBlocking

`writeBlocking` has return values from the function and `writeSynchronous` does not.  
I tested these on the script console and I did notice some difference in response time of the over all execution of a same script.  
Question: Is there a documented/known difference in the performance between these 2 functions ?  
I am interested to know if one can finish writing faster than the other.

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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:** [December 9, 2021, 4:56pm UTC](https://forum.inductiveautomation.com/t/system-tag-writesynchronous-in-ignition-8/24578/5 "2021-12-09T16:56:10Z")

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There is no performance difference, they have the same underlying implementation.