# ModBus tag write not working

**URL:** <https://forum.inductiveautomation.com/t/modbus-tag-write-not-working/23402>\
**Category:** Ignition\
**Created:** [March 18, 2019, 2:28am UTC](https://forum.inductiveautomation.com/t/modbus-tag-write-not-working/23402 "2019-03-18T02:28:42Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![pdixon](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pdixon/32/6899_2.png) [@pdixon](https://forum.inductiveautomation.com/u/pdixon)\
**Post date:** [March 18, 2019, 2:28am UTC](https://forum.inductiveautomation.com/t/modbus-tag-write-not-working/23402/1 "2019-03-18T02:28:42Z")

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I have a Modbus device and can successfully write to Hold Register addresses from the Quick Client:

 ![ig_wrmodbus01](https://us1.discourse-cdn.com/inductiveautomation/original/2X/0/0cec3f53278641c407a03c981b69f98d407a1b7c.jpeg)

I build a tag to that address, with Access Rights set read/write :

 ![ig_wrmodbus02](https://us1.discourse-cdn.com/inductiveautomation/original/2X/3/36745b95fbbc5ac42d3d4c6b3a32ef5325b0fc4a.jpeg)

When I try to change the value I get “Gateway Comm Mode is not Read/Write”

 ![ig_wrmodbus04](https://us1.discourse-cdn.com/inductiveautomation/original/2X/2/284f5e514c660dbdba08745e7b489fa9ababee0e.jpeg)

What is happening?

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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:** [March 18, 2019, 2:34am UTC](https://forum.inductiveautomation.com/t/modbus-tag-write-not-working/23402/2 "2019-03-18T02:34:49Z")

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Change your designer into Read/Write mode. It’s the 3 icons under the “Component” menu.

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**Author:** ![JordanCClark](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/jordancclark/32/83362_2.png) [@JordanCClark](https://forum.inductiveautomation.com/u/JordanCClark)\
**Post date:** [March 18, 2019, 9:50am UTC](https://forum.inductiveautomation.com/t/modbus-tag-write-not-working/23402/3 "2019-03-18T09:50:14Z")

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The default is set by project. You can change it in the project properties.

 ![2019-03-18_5-47-42](https://us1.discourse-cdn.com/inductiveautomation/original/2X/8/86d9f2c71d4e9f8a38eefbf6cfaff4d31c1d218c.jpeg)

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<div class="post-metadata">

**Author:** ![pdixon](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pdixon/32/6899_2.png) [@pdixon](https://forum.inductiveautomation.com/u/pdixon)\
**Post date:** [March 18, 2019, 2:02pm UTC](https://forum.inductiveautomation.com/t/modbus-tag-write-not-working/23402/4 "2019-03-18T14:02:02Z")

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Boom! Thanks, I had forgotten about that