If enabled Freedomotic logs all messages in a file called freedomotic.log located in FREEDOMOTIC_ROOT/log folder.
It is configured to roll if the size is more than 500Kb.
Change the property KEY_SAVE_LOG_TO_FILE in FREEDOMOTIC_ROOT/config/config.xml by choosing one of the following values:
For example
KEY_SAVE_LOG_TO_FILE = ALL
or
KEY_SAVE_LOG_TO_FILE = INFO
Here a log example
date LEVEL [thread] (Class:row) Message
2017-03-27 17:34:10,695 INFO [main] (BusBroker.java:60) Creating new messaging broker
2017-03-27 17:34:10,960 INFO [main] (BusBroker.java:63) Configuring messaging broker
2017-03-27 17:34:11,314 INFO [main] (BusBroker.java:66) Starting messaging broker
2017-03-27 17:34:12,211 INFO [main] (BusConnection.java:96) Creating connection factory
Note
INFO is the best choice in many cases