How to know which device is connected in which /dev/ttyUSB port
You can get this information from the sys filesystem. It is easy to check from the shell, and then do a program that does the same:
cd /sys/devices- Find the directory of the first of your ports:
find -name "ttyUSB0". It will probably find them in something like./pci0000:00/0000:00:1d.0/usb2/2-2/2-2.1/2-2.1:1.0/... The
pci*part is the USB controller. The interesting bit is the2-2.1which is the USB device. In that directory there are a lot of files that identify your device:serial: The serial number. Probably what you want.idVendorandidProduct: The USB identifier of the device.
An easy alternatively to steps 1 and 2 is:
cd /sys/class/tty/readlink ttyUSBnwill give you the full path of the device directory.
As a footnote, note that some parts of the sysfs are considered API stable and some parts are not. For more information see the official sysfs rules.