thank you for your reply!
No my device doesn't have an MQTT connection, I have the TTRB142 for that. I want to send serial RS232 data from my device to MQTT through the TRB142, but up to now I was able just to send Modbus data, no way for "normal" SERIAL RS232 data.
I was able to send serial RS232 data from my device to an IP address (with Putty connected to TRB's mobile IP), but also in this case I wasn't able to send the serial data to MQTT.
So my configuration should be the following:
[RS232 Serial Device] -> [TRB142] -> [MQTT Server]
Thank you in advance