# Error writing to tag Bad\_ReadOnly **URL:** \ **Category:** Ignition\ **Created:** [February 16, 2024, 5:52am UTC](https://forum.inductiveautomation.com/t/error-writing-to-tag-bad-readonly/85806 "2024-02-16T05:52:32Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Harrison\_Ting](https://avatars.discourse-cdn.com/v4/letter/h/48db29/32.png) [@Harrison\_Ting](https://forum.inductiveautomation.com/u/Harrison_Ting)\ **Post date:** [February 16, 2024, 5:52am UTC](https://forum.inductiveautomation.com/t/error-writing-to-tag-bad-readonly/85806/1 "2024-02-16T05:52:32Z")
So I created the project in the office, backed it up and restored on new machine onsite. Everything looks good until I tried a few function that write to the PLC and got this error "Error writing "XX" to tag ...... Bad\_ReadOnly. Happen with client as well as in the designer tag browser. Probably missing something stupid simple. Version is 8.1.37, the latest now. ---
**Author:** ![Hayden\_Watson](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/hayden_watson/32/48792_2.png) [@Hayden\_Watson](https://forum.inductiveautomation.com/u/Hayden_Watson)\ **Post date:** [February 16, 2024, 7:15am UTC](https://forum.inductiveautomation.com/t/error-writing-to-tag-bad-readonly/85806/2 "2024-02-16T07:15:10Z")
Maybe dumb question, but is the tag set to read only? ---
**Author:** ![Harrison\_Ting](https://avatars.discourse-cdn.com/v4/letter/h/48db29/32.png) [@Harrison\_Ting](https://forum.inductiveautomation.com/u/Harrison_Ting)\ **Post date:** [February 16, 2024, 5:22pm UTC](https://forum.inductiveautomation.com/t/error-writing-to-tag-bad-readonly/85806/3 "2024-02-16T17:22:18Z")
No, not a bad question at all. This is only my 2nd project on Ignition so probably something stupid on my part. The first one was a tiny 3 screens Edge Panel. This one does have 2 clients. The HMI tag is not set to read only. The Logix PLC tag is set to read and write. I don't see an option associated with client launch too set to read only but in the Designer I know you can set to Comm Off/Read Only/Read-Write and it's set to Read-Write. I set up the gateway, looked at it then walked away to set up the client and that's when I realized that I got a problem so I'm not sure this same issue exist at the gateway machine itself. I intend to check that next week. ---
**Author:** ![lrose](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/lrose/32/62724_2.png) [@lrose](https://forum.inductiveautomation.com/u/lrose)\ **Post date:** [February 16, 2024, 5:47pm UTC](https://forum.inductiveautomation.com/t/error-writing-to-tag-bad-readonly/85806/4 "2024-02-16T17:47:01Z")
> [@Harrison\_Ting](#): > > The Logix PLC tag is set to read and write Is the tag in the PLC set for external access? ---
**Author:** ![Harrison\_Ting](https://avatars.discourse-cdn.com/v4/letter/h/48db29/32.png) [@Harrison\_Ting](https://forum.inductiveautomation.com/u/Harrison_Ting)\ **Post date:** [February 16, 2024, 6:21pm UTC](https://forum.inductiveautomation.com/t/error-writing-to-tag-bad-readonly/85806/5 "2024-02-16T18:21:13Z")
Yes, external access is allowed in Logix. This is a iFix to Ignition conversion so nothing in PLC has changed. Also, this worked just fine on the workbench. ---
**Author:** ![Harrison\_Ting](https://avatars.discourse-cdn.com/v4/letter/h/48db29/32.png) [@Harrison\_Ting](https://forum.inductiveautomation.com/u/Harrison_Ting)\ **Post date:** [February 20, 2024, 10:38pm UTC](https://forum.inductiveautomation.com/t/error-writing-to-tag-bad-readonly/85806/6 "2024-02-20T22:38:21Z")
Found it, tech support had me checking a few things and it's Config \> OPC \> OPC Connections and make sure that the OPC UA Server that the tags are coming from is not set to Read Only.