How to know which device is connected in which /dev/ttyUSB port

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http://stackoverflow.com – I am using two wavecom modem having 16 ports in each. When i attach modem with my machine, i am able to get list of all /dev/ttyUSB port name, but i want to know also, which modem is containing port 0 to 16 and which one is containing 17 to 32 ? This modem is going to attached and removed many time in single day, so i also want to keep watch , when modem get disconnected and connected again ? Any idea how to do so using c/c++/php script/node.js ? (HowTos)