Send message via node from MQTT

[Slyke]

So on the nodes I have:

• MQTT Enabled: true
• Proxy (MQTT) to client: tried true and false when connected to wifi or BLE
• OK to MQTT: tried with true and false.
• Uplink: true
• Downlink: true
• Default topic: msh/US
• Encryption Enabled: tried with true and false.

---

MQTT Attempts:

Topic: msh/US/2/json/mqtt/!9e0a0718
Payload: {"from": 2651457304, "payload": "hi"}

Topic: msh/US/2/json/mqtt/
Payload: {"from": 2651457304, "payload": "hi"}

Topic: msh/US/2/json/mqtt/
Payload: {"from": "!9e0a0718", "payload": "hi"}

Topic: msh/US/2/json/mqtt
Payload: {"from": 2651457304, "payload": "hi"}

Topic: msh/US/2/json/mqtt
Payload: {"from": "!9e0a0718", "payload": "hi"}

There is conflicting instructions on Meshtastic's official documentation (particularly in topic and payload).

My sources:

• https://meshtastic.org/docs/software/integrations/mqtt/nodered/ (Topic: msh/US/2/json/mqtt, No flow for sending, just for receiving)
• https://meshtastic.org/docs/software/integrations/mqtt/home-assistant/#home-assistant-integrations-for-meshtastic (Topic: msh/US/2/json/mqtt/!<NodeId>)
• https://meshtastic.org/docs/software/integrations/mqtt/ (Topic: msh/US/2/json/mqtt)

I also found this thread: https://www.reddit.com/r/meshtastic/comments/1aukc64/anyone_had_succes_sending_meesage_originating/

But didn't help.

I've tested on 2x T-Decks, a T-Echo, Heltic v3 and a T-Beam Supreme. All running the latest betas 2.6.4.b89355f, 2.5.20.4c97351 etc.

Not sure what I'm doing wrong.

[garthvh]

JSON is for a home assistant integration, generally you need to be using a meshtastic app to send messages over mqtt, there are some scripts that do some simple messaging over mqtt only, but no complete clients.

[Slyke]

Yeah, don't need anything fancy, just need to know the payload and topic the nodes listen on. Do you know of any that work? The node will be connected to MQTT over wifi.

[garthvh]

Yeah, don't need anything fancy, just need to know the payload and topic the nodes listen on. Do you know of any that work? The node will be connected to MQTT over wifi.

If your node is on WiFi and connecting to the public server you need to turn off tls, json and the proxy

[Slyke]

Nahh, I'm using my own MQTT server. There's no TLS. I can see all my nodes posting messages to MQTT, but no matter the payload and topic, none of them ever send messages from MQTT. I'm using MQTT Explorer and NodeRed when sending the MQTT payloads. I'm following the NodeRed and Home Assistant documentation for payload and topics, but none of my nodes ever send a message. In fact I don't even see them saying they received a MQTT payload in the serial monitor, which to me indicates I'm not publishing to the correct topic.

I essentially want to send a message to a specific node, or a channel from NodeRed, but prefer doing it via MQTT, so other software can also utilise it.

Nodes can see each other over MQTT, and also have LoRa links with each other.

The NodeRed flow I'm using is pretty basic. You can see all the experimenting I've been doing:

[GUVWAF]

Any of the topics you mentioned should work, the node ID in the topic is not necessary per se.

You are missing the "type" in your payload, see: https://meshtastic.org/docs/software/integrations/mqtt/#json-downlink-to-instruct-a-node-to-send-a-message

E.g.
{"from": 2651457304, "type": "sendtext", "payload": "hi"}

Also, did you actually make a channel named "mqtt" and enabled downlink there, and do you have JSON enabled?

[sirg]

Having the same problem (I think): private/local MQTT broker (plain vanilla, no auth, no encryption, local hostname 'www'), Heltec_v3 flashed with 2.6.11, configured on WiFi, channel 'mqtt' enabled with both uplink and downlink, MQTT configured with JSON, no encryption/TLS, root 'msh/US'. Messages entered into the channel from gateway or another node are visible to subs to the MQTT broker.
Sending with: echo '{ "from":3679551200,"type":"sendtext","payload":"Test 251129T035800"}' | mosquitto_pub -h www -t 'msh/US/2/json/mqtt' -s - visible to subscribers, but not appearing on the channel.

How do I troubleshoot this?