# MQTT bridge - SmartApp does not trigger DH

**URL:** <https://community.smartthings.com/t/mqtt-bridge-smartapp-does-not-trigger-dh/167834>\
**Category:** Writing SmartApps\
**Tags:** mqtt\
**Created:** [July 9, 2019, 9:08am UTC](https://community.smartthings.com/t/mqtt-bridge-smartapp-does-not-trigger-dh/167834 "2019-07-09T09:08:57Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![DerekC](https://yyz2.discourse-cdn.com/smartthings/user_avatar/community.smartthings.com/derekc/32/100200_2.png) [@DerekC](https://community.smartthings.com/u/DerekC)\
**Post date:** [July 9, 2019, 9:08am UTC](https://community.smartthings.com/t/mqtt-bridge-smartapp-does-not-trigger-dh/167834/1 "2019-07-09T09:08:57Z")

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I found this bridge [https://github.com/stjohnjohnson/smartthings-mqtt-bridge/issues/205](https://github.com/stjohnjohnson/smartthings-mqtt-bridge/issues/205) but it seems the author is no longer active.

I’m trying to get this working and was wondering if anyone here could help.

I can see the SmartApp is getting the on / off signal, and it’s trying to call the DH - but in the DH there are debug statements that never fire…

Is there any docs on how to call a DH from inside the SmartApp?

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**Author:** ![DerekC](https://yyz2.discourse-cdn.com/smartthings/user_avatar/community.smartthings.com/derekc/32/100200_2.png) [@DerekC](https://community.smartthings.com/u/DerekC)\
**Post date:** [July 12, 2019, 7:22am UTC](https://community.smartthings.com/t/mqtt-bridge-smartapp-does-not-trigger-dh/167834/2 "2019-07-12T07:22:42Z")

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For anyone else interested, I move the hubAction call from the DH into the smartApp. I can get the hub to trigger the rest call to my mqtt-bridge.

I’m now working on the call from mqtt -\> bridge -\> hub -\> ST.

Of course, we could just use the ST rest service, but I am still trying to get the call to the hub to work.

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**Author:** ![nivekmai1](https://yyz2.discourse-cdn.com/smartthings/user_avatar/community.smartthings.com/nivekmai1/32/116713_2.png) [@nivekmai1](https://community.smartthings.com/u/nivekmai1)\
**Post date:** [April 23, 2020, 7:25am UTC](https://community.smartthings.com/t/mqtt-bridge-smartapp-does-not-trigger-dh/167834/3 "2020-04-23T07:25:08Z")

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Probably a useless reply, but I was having trouble getting the smartapp to work at all. Simply opening the smartapp in the android app, turning off one of the allowed devices, turning it back on, and hitting save got everything running properly again.