# Write Only Access Right for Modbus Tag

**URL:** <https://forum.inductiveautomation.com/t/write-only-access-right-for-modbus-tag/25149>\
**Category:** Ignition\
**Created:** [May 20, 2019, 12:24pm UTC](https://forum.inductiveautomation.com/t/write-only-access-right-for-modbus-tag/25149 "2019-05-20T12:24:30Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![nader.chinichian](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/nader.chinichian/32/9261_2.png) [@nader.chinichian](https://forum.inductiveautomation.com/u/nader.chinichian)\
**Post date:** [May 20, 2019, 12:24pm UTC](https://forum.inductiveautomation.com/t/write-only-access-right-for-modbus-tag/25149/1 "2019-05-20T12:24:30Z")

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Hello  
I have Modbus TCP device which has some holding register that is Write Only and use for resting Counter or save the setting of device when Master write the value of 1 on them. The read operation on these address will fail.  
The problem is in ignition defining tag access right group in two read only and read/write.  
The read/write cause Ignition try to read it and cause the tag quality get BAD and subsequently the write operation will fail because of that.  
Is there any workaround for this?

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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [May 20, 2019, 1:06pm UTC](https://forum.inductiveautomation.com/t/write-only-access-right-for-modbus-tag/25149/2 "2019-05-20T13:06:01Z")

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Don’t define a tag in Ignition for that register. Use the `system.opc.write*()` script functions to write directly to that address when needed.