I often use data loggers connected through USB Virtual COM ports that output raw binary data. The typical approach would be to use putty or other terminal emulator to connect to given port and log the data to a file. But this has a major drawback, some bytes in the serial ASCII protocol are control bytes and the emulator won’t write them to the log file. This can be omitted by using stty and cat.

(stty raw; cat > file.log) < /dev/<your_serial_device>

This command will write all raw output data to given file. To run this in the background for a longer time you can use screen to create a session and detach from it.