# Writing to Red Lion PLC via Modbus

**URL:** <https://forum.inductiveautomation.com/t/writing-to-red-lion-plc-via-modbus/110849>\
**Category:** Ignition\
**Tags:** opcua, vision, ignition81, modbus\
**Created:** [September 22, 2025, 7:56pm UTC](https://forum.inductiveautomation.com/t/writing-to-red-lion-plc-via-modbus/110849 "2025-09-22T19:56:06Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![dkhayes117](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/dkhayes117/32/68344_2.png) [@dkhayes117](https://forum.inductiveautomation.com/u/dkhayes117)\
**Post date:** [September 22, 2025, 8:23pm UTC](https://forum.inductiveautomation.com/t/writing-to-red-lion-plc-via-modbus/110849/4 "2025-09-22T20:23:55Z")

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As long as the tag has `Read Only` False, then I can’t imagine why it wouldn’t write if the tags are correctly reading.

Maybe check into this

> [@Red Lion Data Converter DA30D outputs not switching](https://forum.inductiveautomation.com/t/red-lion-data-converter-da30d-outputs-not-switching/93073/9):
>
> I would check the configuration in the RedLion. We typically use them to pass tags directly between devices, but we also typically set them up for one-way communications. It's possible it's rejecting writes to those tags because it simply can't write back depending on the config.

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