@RunThiner There's no need for such a loop. QSerialPort already provides an asynchronous API and if you really want to wait for data to be available, there's a blocking API for that as shown in the QSerialPort details.

@sdcr said: (bites = sp->bytesAvailable()) Although it should return a reference to bites, it is not good coding practice imho. http://en.cppreference.com/w/cpp/language/operator_assignment