# MQTT Transmission

**URL:** <https://forum.inductiveautomation.com/t/mqtt-transmission/44779>\
**Category:** 3rd Party Modules\
**Created:** [March 23, 2021, 6:59am UTC](https://forum.inductiveautomation.com/t/mqtt-transmission/44779 "2021-03-23T06:59:27Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![heshan](https://avatars.discourse-cdn.com/v4/letter/h/b38774/32.png) [@heshan](https://forum.inductiveautomation.com/u/heshan)\
**Post date:** [March 23, 2021, 6:59am UTC](https://forum.inductiveautomation.com/t/mqtt-transmission/44779/1 "2021-03-23T06:59:27Z")

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I can’t seem to find a way to change the default messaging format from SparkPlugB to customisable JSON? Ideally we would like to keep the one same MQTT topic for the whole project and just change the message payload per tag to include metadata and ts / value pair JSON data.

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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:** [March 23, 2021, 12:35pm UTC](https://forum.inductiveautomation.com/t/mqtt-transmission/44779/2 "2021-03-23T12:35:19Z")

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I believe you need to create a custom namespace in the MQTT Engine Module. You should be able to define your custom structure there.

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/6/e/6e6fde3197116de07721b7c4d6841a4bcd0b26ac.png)