# Modbus TCP Driver tags Bad\_ReadOnly

**URL:** <https://forum.inductiveautomation.com/t/modbus-tcp-driver-tags-bad-readonly/96510>\
**Category:** Ignition\
**Tags:** ignition81, perspective, modbus\
**Created:** [September 26, 2024, 5:17pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-driver-tags-bad-readonly/96510 "2024-09-26T17:17:46Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Tyler](https://avatars.discourse-cdn.com/v4/letter/t/35a633/32.png) [@Tyler](https://forum.inductiveautomation.com/u/Tyler)\
**Post date:** [September 26, 2024, 5:17pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-driver-tags-bad-readonly/96510/1 "2024-09-26T17:17:46Z")

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I have just added a Moxa ioLogik E1211 to my Ignition gateway. I am able to read the value ns=1;s=[Moxa]0.C1 but not write to it. when I write I get an error Bad\_ReadOnly but the tag is set to readonly=false. The Moxa indicates that the coil address 0-16 should be RW and I cannot find where this read only is coming from.

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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:** [September 26, 2024, 5:42pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-driver-tags-bad-readonly/96510/2 "2024-09-26T17:42:21Z")

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Is your OPC connection configured as read only?

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<div class="post-metadata">

**Author:** ![Tyler](https://avatars.discourse-cdn.com/v4/letter/t/35a633/32.png) [@Tyler](https://forum.inductiveautomation.com/u/Tyler)\
**Post date:** [September 26, 2024, 6:00pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-driver-tags-bad-readonly/96510/3 "2024-09-26T18:00:02Z")

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Yes it is. I did not realize that was a thing. given the number of other devices on here I would not have imagined that I was the first to attempt a write. How can I write to a device then? do I have to make a second OPC connection?

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/9/8/988d5b80ab4beb864a87d02fa6b496f40c1493c7.png)

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<div class="post-metadata">

**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:** [September 26, 2024, 6:05pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-driver-tags-bad-readonly/96510/4 "2024-09-26T18:05:25Z")

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You could make another... or you could just un-check that. Maybe figure out who set it up that way in the first place and why.