That is weird, your Edison is in fact being recognized by your PC, right? I mean, what appears in the device manager?
According to your description, my guess is that something went wrong with the installation of either the drivers or the IDE itself. You used the unified installer, right? If so, I believe the best possible step is to uninstall everything and install them again separately. Make sure you install the Edison's drivers. You can either choose the Arduino IDE version 1.6.0 (which includes the Galileo/Edison boards by default) or the version 1.6.5 (you have to follow IoT - Install the Arduino* IDE | Intel® Developer Zone to install the Galileo/Edison boards).
Once this process has finished, reboot your PC just to be sure. Now try again.
first thanks for your quick reply!
Yes, the board is recognized by Windows correctly: I see two COM port (both mentioned in my first) post in the device manager when I connect both micro USB ports. Also a Windows Explorer window is opened with a storage when I connect the Arduino to USB. Only the Arduino IDE does not like to recognize it correctly!
To be honest I thought about installing everything manually before using your installer, but then I thought you probably thought about what needs to be installed in what order and therefore it's best to use your unified installer - it's a bit disappointing that this obviously was the wrong decision.
I now uninstalled everything again, and download and installed the Arduino IDE 1.6.5 manually. Then I needed the drivers for the Edision board again and and installed the stand-alone drivers from here:
Now I can upload a sketch from the Arduino IDE, but when I connect the second (outer) micro-USB port, I get an incompatible driver warning sign in the device manager at the "USB Serial Port" which was not there after the first installation (although at that time the sketch upload did not work and now it works). So now I have the "Intel Edision Virtual Com Port" device working (and sketch upload as well), but the "USB Serial Port" device (when the outer micro-USB connector is used as well) not.
What I need the outer USB-micro port (and the "USB Serial Port" device) for?
Is that needed for the Arduino serial monitor?
And any idea why that's not recognized now anymore?
Do I need an additional driver for that?
Best regards and thanks again for your support
The outer USB port is to connect using a serial application such as Putty. This is a HUGE help in determining if you're on wifi, the /sketch/sketch.elf file has correct permissions (or exists at all), rebooting without unplugging, etc. I have had issues like this before and the magic trick was to change my USB cable. I now have a very high quality USB 2.0 cable that I have marked and always use for my serial connection. Also, on the power side, make sure you're not plugging into a USB supply that is greater than 3.3 volts. My pc has a "quick charge" USB port (5.5V) and if I use it the Edison just reboots constantly.
Hope this helps!
I'm glad to hear that you are now able to upload sketches to your Edison.
The USB serial port is used to access the Edison's internal Linux through PuTTY (or any other similar program). The reason why your PC may not be recognizing your Edison might be because of a missing driver. If seantibb's suggestion doesn't work, try installing the FTDI driver by following the guide for your OS in FTDI Installation Guides.