Please check if the terminal is set properly, so as to receive both carriage return (\r) and line feed (\n). If line feed is not received then the previous data will be overwritten. Are you receiving approximately the same number of bytes expected (sent)?
You can install and use minicom terminal which is just like tera term in windows. Please refer to this link : USB CDC with the Raspberry Pi | MCU on Eclipse
thanks the setup is now OK, I can use the RaspberryPI 3 . problem was not strictly related to LineFeed but on how converters were powered. power was not completely off when we thought it was, apparently then the converter at the next startup was sending data retained after the failed power off.