# MQTT Tag Structure

**URL:** <https://forum.inductiveautomation.com/t/mqtt-tag-structure/59136>\
**Category:** Ignition\
**Created:** [May 2, 2022, 8:45pm UTC](https://forum.inductiveautomation.com/t/mqtt-tag-structure/59136 "2022-05-02T20:45:18Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Paul\_Goodsell](https://avatars.discourse-cdn.com/v4/letter/p/f1d935/32.png) [@Paul\_Goodsell](https://forum.inductiveautomation.com/u/Paul_Goodsell)\
**Post date:** [May 2, 2022, 8:45pm UTC](https://forum.inductiveautomation.com/t/mqtt-tag-structure/59136/1 "2022-05-02T20:45:18Z")

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Hi I am setting up a new ignition system, making use of MQTT, several sites (1000 tags per site). I am after some advice on the best way to set up the Tag structure. My objective is to create 1 PLC / Edge Project and copy this across the 100+ sites, renaming each project uniquely. The query I have is with regards to limiting the MQTT data, for example I have an Analogue sensor and 4 off associated Boolean alarms (HiHi, Hi, Lo, LoLo) that are initiated in the PLC. I was going to setup the edge device / MQTT with only the data from the PLC that changes (Analogue Value, HiHi, Hi, Lo, LoLo). I was then going to setup a duplicate Gateway Tag database with bindings to the MQTT Tags in a relevant UDT structure, with additional memory / derived Tags. For the above example I was going to create an Analogue UDT in the gateway that would hold the additional information, Tag description, alarm setpoints (for display), historical database, alarming, engineering range etc.

Or should I create the UDT structure in the Edge Gateway device and rely on the MQTT.

The objective I have is to roll out additional sites with minimal rework, cost to the client