MQTT Modbus Gateway - Thingsboard RPC Timeout

[DIssia]

Hello,

I’ve configured succesfully on RUT300 Data to server to send telemetry data to thingsboard, but I have a problem with MQTT Modbus Gateway, if I send an RPC from thingsboard goes in timeout and the rut doesn’t receive nothing. Here’s my configuration on the router

where I’m wrong? I’ve tested using MQTTX tool replacing Host with: broker.emqx.io and it’s work using the same topic.

Thanks

[DIssia]

Ok, I’ve been able to connect correctly with MQTT, but obviously I obtain Failed Request.

I’ve followed this Topics:

Help with JSON Format for MQTT Modbus Gateway on RUT956 (ThingsBoard Integration)

Hello, Hardware: RUT956 Firmware version: RUT9M_R_00.07.14.3 I’m trying to integrate a Teltonika RUT956 with ThingsBoard using Modbus TCP and MQTT for bidirectional communication. What I’ve tried: I found the following JSON example in the community, now i’ m intended to switch a relay (integrated in router) ON/OFF via MQTT (tested with MQTT Explorer): { "cookie": 65432, "type": 0, "host": "192.168.1.1", "port": 502, "timeout": 5, "server_id": 1, "function": 6, "register_num…

MQTT Modbus to Thingsboard

Hello, I’ve checked this with our development team, and I’d like to share some insights. Currently, the Modbus MQTT Gateway service supports only two predefined data formats, and unfortunately, it isn’t natively adjustable through the WebUI in the way you described for customizing RX messages. However, there’s a workaround solution developed by our programmer available by implementing a custom Lua service acting as a bridge between ThingsBoard and the device’s Modbus MQTT gateway. This Lua scr…

But unfortunately I can’t install lua packages and I can’t make the workaround.

There is a solution or lua packages compatible with RUT300?

[anon65719490]

Hello,

For testing, could you please try setting the QoS level to 2 in your MQTT configuration?

Also, just to confirm, are you using the same broker (ThingsBoard) for both the MQTT Gateway and Data to Server services?

It would be great if you could share the ThingsBoard RPC request log.

Additionally, for testing purposes, try entering your ThingsBoard device access token as the username, and set the Client ID to match your device name.

Could you also confirm whether JSON parsing is enabled for RPC requests on your ThingsBoard instance?

Finally, if possible, please share a screenshot of your ThingsBoard device configuration.

Best regards,

[DIssia]

Hello Martynas and thanks for the quick reply.

I’ve performed all the requested checks.
Here are the results and current configuration details:

• QoS: Set to Exactly once (2) for the MQTT Gateway.

• Broker: Both the MQTT Gateway and the Data-to-Server service use the same broker – mqtt.eu.thingsboard.cloud on port 1883.

• Message type / JSON parsing: The message type is JSON, so RPC messages are sent in JSON format.

• Client ID: Matches the client ID taken from thingsboard (fmiobmepzgvlb0awbjd2).

• RPC log: Shows correct IN/OUT messages with ACK and Success events from ThingsBoard.

I also tested using the device access token (copied from “Copy MQTT credentials”) as username and the device name as Client ID — with this configuration the MQTT connection works correctly, but Teltonika reports a Failed request.

However, when I use the device ID (copied from “Copy device ID”) as username, the MQTT connection remains down and never establishes.

At this point, I believe the issue may be related to how ThingsBoard sends the RPC payload.
It seems that the Teltonika MQTT Modbus Gateway expects only the JSON object inside the “params” key rather than the complete RPC structure ({method, params, additionalInfo}).

Could you please clarify what you mean by: “confirm whether JSON parsing is enabled for RPC requests on your ThingsBoard instance”? Because actually I’ve just configured an RPC button on the dashboard, here the configuration:

Screenshots of all configurations and logs are attached for reference.

Data to server config, works and send telemetry to thingsboard:

MQTT Gateway config 1: Receive something but fails ( is the RPC payload wrong?)

TB RPC Log:

TB RPC Payload:

MQTT Gateway Config 2: doesn’t connect

TB Device Config:

[DIssia]

Hello @anon65719490,

I hope I have provided all the answers in the previous post. If anything is missing, please let me know. Thank you.