TRB255 - Modbus mqtt gateway and data to server

Hello everybody,

is it possible to use the “data to server” function and the “Modbus mqtt gateway” at the same time?

I need to read some parameters from a solar inverter via modbus TCP and pass it to a SCADA; i want to
setup the TRB255 to perform the readings and then send them to the SCADA via “data to server”.

At the same time i need to send modbus commands to the inverter (in this case i need the Modbus mqtt gateway function).

Can the 2 functions cohexist?

Thanks in advance!


Yes, both of these functions can be used at the same time when Modbus TCP is used. This will not work with Modbus RTU, as there will be a conflict for the serial interface.

Best regards,

Hello Daumantas,

Thank you for the quick reply! I tried to setup an automated reading of a parameters of the inverter in “modbus TCP master” and a data sender in “Data to server” and it works.
I have another question: it seems that the TRB 255, if the data to server function is active, but not connecting to the server (bad connection parametrs settings…) puts all the data read in a buffer and when the data to server functions starts, it sends all the "old data collected…
There’s a way to prevent this?

Thank you.


Yes, the modbus data is being collected in volatile memory, and once the connection is restored it will be sent to the server. One way you could try avoiding this, is disabling the “Retry on fail” option in the Data to Server, as well as using the QoS 0 on MQTT. However, I’m not sure if this will fully mitigate the issue.
If you are experienced in shell scripting, you could use a script to delete the Modbus database file from /tmp every X amount of minutes.

Best regards,

“retry on fail” is already disabled and unfortunately i don’t have experience with scripts… there’s an exmple somewhere in the Teltonika wiki?

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