I did not yet upgrade to 3.1 yet due to one of the most important bindings for me (not official eBus binding) not being compatible yet with it. However that changed last week, so it is time to install 3.1 in a test environment to do some testing 
In the mean time I am trying to take a new approach towards the serial device by requesting the rain value every minute and performing a reset of the optical rain sensor every midnight. Maybe that sending a command regularly will keep the receipt of messages going.