Access to payload from MQTT

Hi,
I have an application that recives data from 3 sensors. Here an example of received data.

Note I’m interested mainly in the information in “frm_payload” for further decoding and processing.

I’ve also added the MQTT integration and I’m able to connect to it with MQTT Explorer. When we explore the topics and info in the Explorer, we recive information from topics “up” and “log”, but none of them includes the field “frm_payload”, that is the one I’m interesting in. Here an example of the MQTT Explorer view:

I’m not sure how these packet types are processed by chirpstack, the differences between “up/log” and “confirmedDataUp”, and if I need to do something else in order to be able to access to “frm_payload” from a MQTT subscriber. Can you point me to some document or example about how to proceed?

Thanks and best regards

Not confident here but I think it’s just called “data” in the MQTT payload. Also you can add a decoder to your device profile so it processes the data into more readable JSON strings.