@aha_1980 Thank you so much for your ideas. Both problems solved. After reconfiguring aptitude stuff to use "stable" instead of hard-coded "jessie" and half-a-day-long upgrades and cleaning the mess I really got not only higher version of Qt, but as well QParallelPort working as planned. Definitely worth the effort (even if I did not expect the upgrade to take so much time.) My mistake. I missed this single character overload to append(). Thank you for pointing me there. Now I got completely rid of that development/release conditionals. Case closed, thanks to all who assisted.

You're welcome ! Since you have it working now, please mark the thread as solved using the "Topic Tools" button so that other forum users may know a solution has been found :)

yes it should. you can read about it here http://manpages.ubuntu.com/manpages/utopic/man1/pumount.1.html it seems to expect the device to be mounted under /media.

@SGaist I'm not sure, but I believe solid needs udev. I'm using busybox with mdev. However, I found a solution with find and grep. If I know I have to find where, for instance, sda is connected on my 4 ports: find /sys/bus/usb/devices/usb*/ -name dev -path "*usb1*sd*" | grep -E sda find /sys/bus/usb/devices/usb*/ -name dev -path "*usb2-1.1*sd*" | grep -E sda find /sys/bus/usb/devices/usb*/ -name dev -path "*usb2-1.2*sd*" | grep -E sda find /sys/bus/usb/devices/usb*/ -name dev -path "*usb2-1.4*sd*" | grep -E sda The return value is 1 if there is no entry matching and 0 if there is. I wrapped this in a function with sd_ as variable and it works as supposed. Cheers, McL

http://api.kde.org/frameworks-api/frameworks5-apidocs/solid/html/index.html

Exact, QSerialPort doesn't call the USB stack directly. Typically for FTDI devices, you would install the FTDI Virtual Com Port driver and then you have a "classic" com port. AFAIK the ARDUINO uses RS232 so it should act also like a serial device.