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I am using two Wavecom 16-port modems. When I attach the modems to my system, I am able to list of all the /dev/ttyUSB port names, but also I want to know, which modem is containing ports 0 to 16 and which one is containing ports 17 to 32?

The modems may be attached and removed many times in a single day, so I also want to keep logs when modems get disconnected and connected again.

Any idea how to do so using c/c++/php script/node.js ?

Alex P.
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Mayur
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  • it is much easier to set up `udev` rules to assign persistent `tty` port names once and for all instead of having to look them up every time – Alex P. Jun 08 '18 at 16:15

1 Answers1

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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:

  1. cd /sys/devices
  2. 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/...

  3. The pci* part is the USB controller. The interesting bit is the 2-2.1 which 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.
    • idVendor and idProduct: The USB identifier of the device.

An easy alternatively to steps 1 and 2 is:

  1. cd /sys/class/tty/
  2. readlink ttyUSBn will 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.

rodrigo
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