Hi!
I have several Teltonika devices that I use to send data from Modbus meters to an MQTT server. I use a Modbus TCP query with the device’s built-in Modbus query and then send this data using the “Data to server” function. I have 5 TRB140 type routers and it works without any problems. I have 3 routers of type RUT300, but all Modbus queries run with errors.
All settings match in working and non-working devices, the 07.14.2 firmware is running on all of them. The meters to query are also identical.
So if everything is identical, why does the Modbus TCP Client query fail on the RUT300? With this in mind, if anyone has any advice or experience in solving this, I would appreciate it!
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Good afternoon,
Could you please clarify what firmware version you are using? Please install the newest one.
Communication failures often stem from network issues such as blocked ports or firewall settings, even if ping works fine. Ensure that the RUT300 devices have unrestricted access to port ports on the Modbus meters.
Verify network connectivity specifically on port 502 from the RUT300 to the Modbus meters. Use tools or logs to confirm Modbus TCP requests are sent and responses received.
Compare detailed Modbus query logs or debug output on both device types to identify where the failure occurs (e.g., no request sent, no response, or invalid response).
Test using the MQTT Modbus Gateway feature on RUT300 (if applicable) to see if relaying Modbus over MQTT works better or reveals different error messages.
If possible, isolate the RUT300 on a simple test network with the Modbus meters to rule out network infrastructure issues.
Regards,
Arturas