I have two same servers (Dell PowerEdge 1850) with Ubuntu 16.04.3 LTS. I tried connect my RFID device to the one server and everything works perfect. I could see device with: dmesg | grep tty. But when I tried on the second server it doesn't work. On both servers is same OS and BIOS. But with lsusb command I can see the device is connected I'm new in Linux OS.Response on working serverpetscanner2@petscanner2:~$ dmesg | grep tty[    0.000000] console [tty0] enabled[    1.300640] 00:02: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A[   31.911685] cdc_acm 1-3.2:1.0: ttyACM0: USB ACM deviceresponse on not working serverpetscanner1@petscanner1:~$ sudo dmesg |grep tty[    0.000000] console [tty0] enabled[    1.278130] 00:02: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A[    1.332193] tty tty14: hash matchesThank you LukasUPDATE 1I run command dmesg and got this error petscanner1@petscanner1:~$ dmesg[   90.960027] usb 1-3.2: new full-speed USB device number 3 using ehci-pci[   91.055665] usb 1-3.2: New USB device found, idVendor=04d8, idProduct=000a[   91.055671] usb 1-3.2: New USB device strings: Mfr=1, Product=2, SerialNumber=0[   91.055676] usb 1-3.2: Product: CDC RS-232 Emulation Demo[   91.055679] usb 1-3.2: Manufacturer: Microchip Technology Inc.[ 1805.541979] blk_update_request: I/O error, dev fd0, sector 0[ 1805.542081] floppy: error -5 while reading block 0[ 1818.605876] blk_update_request: I/O error, dev fd0, sector 0[ 1818.605969] floppy: error -5 while reading block 0
Serial port doesn't work
ubuntu;usb;tty;serial port