I opened an issue in github also. RFlink protocol is here http://www.rflink.nl/blog2/protref The error message is referred to the message show above, this one 20;4e;Alecto V1;ID=0005;WINDIR=0012;WINGS=001c;BAT=OK;\r 20 mean a messagr from RFlink 4e is the message number ID is the sensor ID WINDIR is the wind direction WINGS is the wind speed gust Al messages are in ASCIII, there is not any NaN or strange values like the DHT ones. It happens with all WINDIR messages, no one is decoded. Data are captured and decoded from a meteo station sensors at 433MHz But you give me a good suggestion, maybe there is a character in message not printed in the error, so I will check on a PC in HEX also. Edit: Check done, all ascii chars plus CR+LF at the end I don't understand why this happens on this message and not with others. I watched on my controllers code and I don't see any bug.