I figured it out, it is my poor knowledge of all of this stuff; blame on me.I am finally integrating the jbdtool into a NodeRed flow to send the battery data to an MQTT broker and then SignalK.
To accomplish this I use this command: jbdtool -t serial:/dev/ttyOP_electron -m localhost:electron:vessels/self/battery/bat1 -J
The MQTT receives the data but the content is Null.
It seems that the word 'vessels' inside the topic is maybe considered a reserved word?
If I use the topic written slightly different, like 'vesselt' it works fine.
I have attached an MQTT capture to show that with the word 'vessels' the content is Null, instead with the word 'vesselt' the content is the actual battery data. Even with other words works fine, this is why I thought to a reserved word.
Anyone has a clue, please?
Thanks in advance
Digging down I understood that the SignalK mqtt plugin, writes directly into SignalK keys and for that specific mqtt topic it accepts only numeric values, so any string is passed as null.