Hello, I am trying to use QSerialDevice in Qt to get a connection to my serial port. I also tried QextSerialPort before (which works on Windows Vista but unfortunately not on Windows XP ..) but I need an API which supports XP, Vista and Win7... I build the library and configured it this way: CONFIG += dll CONFIG += debug I did use the current version from SVN (0.2.0 - 2010-04-05) and the 0.2.0 zip package. After building the library I did copy it to my Qt Libdir (C:\Qt\2009.05\qt\lib) and also to C:\Windows\system32. Now I try to link against the lib in my project file: LIBS += -lqserialdevice I import the needed header (abstractserial.h) and use my own AbstractSerial like this: // Initialize this->serialPort->setDeviceName("COM1"); if (!this->serialPort->open(QIODevice::ReadWrite | QIODevice::Unbuffered)) qWarning() << "Error" << this->serialPort->errorString(); // Configure SerialPort this->serialPort->setBaudRate(AbstractSerial::BaudRate4800); this->serialPort->setDataBits(AbstractSerial::DataBits8); this->serialPort->setFlowControl(AbstractSerial::FlowControlOff); this->serialPort->setParity(AbstractSerial::ParityNone); this->serialPort->setStopBits(AbstractSerial::StopBits1); The problem is, that if I run my application, it crashes immediately with exit code -1073741515 (application failed to initialize properly). This is the same error I got using QextSerialPort under Windows XP (it worked with Windows Vista). If I build the QSerialDevice lib with release config and also my program, it crashes immediately but with exit code -1073741819 Can someone help me with this program or with another solution of getting a serial port to work with Qt (maybe another API or something?) Otherwise I have to use Windows API functions which would mean that my program won't work with UNIX systems.. If you have a solution for the problem with QextSerialPort under WinXP SP3, they are also welcome ;) Best Regards, Tobias