This is asked many a times before, but I haven't found any workable solution for my case. In my case, I have got two FTDI based USB <-> Serial converters from which I could not find any distinguishing feature to include in udev rules that I intend to write in order to identify them with a persistent name. The outputs of:
udevadm info --attribute-walk --path=/sys/bus/usb-serial/devices/ttyUSB0
looking at parent device '/devices/pci0000:00/0000:00:14.0/usb3/3-1/3-1:1.0':
KERNELS=="3-1:1.0"
SUBSYSTEMS=="usb"
DRIVERS=="ftdi_sio"
ATTRS{bInterfaceClass}=="ff"
ATTRS{bInterfaceSubClass}=="ff"
ATTRS{bInterfaceProtocol}=="ff"
ATTRS{bNumEndpoints}=="02"
ATTRS{supports_autosuspend}=="1"
ATTRS{bAlternateSetting}==" 0"
ATTRS{bInterfaceNumber}=="00"
ATTRS{interface}=="USB <-> Serial"
looking at parent device '/devices/pci0000:00/0000:00:14.0/usb3/3-1':
KERNELS=="3-1"
SUBSYSTEMS=="usb"
DRIVERS=="usb"
ATTRS{bDeviceSubClass}=="00"
ATTRS{bDeviceProtocol}=="00"
ATTRS{devpath}=="1"
ATTRS{idVendor}=="0403"
ATTRS{speed}=="12"
ATTRS{bNumInterfaces}==" 1"
ATTRS{bConfigurationValue}=="1"
ATTRS{bMaxPacketSize0}=="8"
ATTRS{busnum}=="3"
ATTRS{devnum}=="21"
ATTRS{configuration}==""
ATTRS{bMaxPower}=="90mA"
ATTRS{authorized}=="1"
ATTRS{bmAttributes}=="80"
ATTRS{bNumConfigurations}=="1"
ATTRS{maxchild}=="0"
ATTRS{bcdDevice}=="0400"
ATTRS{avoid_reset_quirk}=="0"
ATTRS{quirks}=="0x0"
ATTRS{version}==" 1.10"
ATTRS{urbnum}=="11"
ATTRS{ltm_capable}=="no"
ATTRS{manufacturer}=="FTDI"
ATTRS{removable}=="removable"
ATTRS{idProduct}=="6001"
ATTRS{bDeviceClass}=="00"
ATTRS{product}=="USB <-> Serial"
looking at parent device '/devices/pci0000:00/0000:00:14.0/usb3':
KERNELS=="usb3"
SUBSYSTEMS=="usb"
DRIVERS=="usb"
ATTRS{bDeviceSubClass}=="00"
ATTRS{bDeviceProtocol}=="01"
ATTRS{devpath}=="0"
ATTRS{idVendor}=="1d6b"
ATTRS{speed}=="480"
ATTRS{bNumInterfaces}==" 1"
ATTRS{bConfigurationValue}=="1"
ATTRS{bMaxPacketSize0}=="64"
ATTRS{authorized_default}=="1"
ATTRS{busnum}=="3"
ATTRS{devnum}=="1"
ATTRS{configuration}==""
ATTRS{bMaxPower}=="0mA"
ATTRS{authorized}=="1"
ATTRS{bmAttributes}=="e0"
ATTRS{bNumConfigurations}=="1"
ATTRS{maxchild}=="4"
ATTRS{bcdDevice}=="0313"
ATTRS{avoid_reset_quirk}=="0"
ATTRS{quirks}=="0x0"
ATTRS{serial}=="0000:00:14.0"
ATTRS{version}==" 2.00"
ATTRS{urbnum}=="383"
ATTRS{ltm_capable}=="no"
ATTRS{manufacturer}=="Linux 3.13.0-32-generic xhci_hcd"
ATTRS{removable}=="unknown"
ATTRS{idProduct}=="0002"
ATTRS{bDeviceClass}=="09"
ATTRS{product}=="xHCI Host Controller"
looking at parent device '/devices/pci0000:00/0000:00:14.0':
KERNELS=="0000:00:14.0"
SUBSYSTEMS=="pci"
DRIVERS=="xhci_hcd"
ATTRS{irq}=="40"
ATTRS{subsystem_vendor}=="0x17aa"
ATTRS{broken_parity_status}=="0"
ATTRS{class}=="0x0c0330"
ATTRS{enabled}=="1"
ATTRS{consistent_dma_mask_bits}=="64"
ATTRS{dma_mask_bits}=="64"
ATTRS{local_cpus}=="ff"
ATTRS{device}=="0x1e31"
ATTRS{msi_bus}==""
ATTRS{local_cpulist}=="0-7"
ATTRS{vendor}=="0x8086"
ATTRS{subsystem_device}=="0x3977"
ATTRS{d3cold_allowed}=="1"
looking at parent device '/devices/pci0000:00':
KERNELS=="pci0000:00"
SUBSYSTEMS==""
DRIVERS==""
and same when done for ttyUSB1:
udevadm info --attribute-walk --path=/sys/bus/usb-serial/devices/ttyUSB1
looking at device '/devices/pci0000:00/0000:00:14.0/usb3/3-2/3-2:1.0/ttyUSB1':
KERNEL=="ttyUSB1"
SUBSYSTEM=="usb-serial"
DRIVER=="ftdi_sio"
ATTR{port_number}=="0"
ATTR{latency_timer}=="1"
looking at parent device '/devices/pci0000:00/0000:00:14.0/usb3/3-2/3-2:1.0':
KERNELS=="3-2:1.0"
SUBSYSTEMS=="usb"
DRIVERS=="ftdi_sio"
ATTRS{bInterfaceClass}=="ff"
ATTRS{bInterfaceSubClass}=="ff"
ATTRS{bInterfaceProtocol}=="ff"
ATTRS{bNumEndpoints}=="02"
ATTRS{supports_autosuspend}=="1"
ATTRS{bAlternateSetting}==" 0"
ATTRS{bInterfaceNumber}=="00"
ATTRS{interface}=="USB <-> Serial"
looking at parent device '/devices/pci0000:00/0000:00:14.0/usb3/3-2':
KERNELS=="3-2"
SUBSYSTEMS=="usb"
DRIVERS=="usb"
ATTRS{bDeviceSubClass}=="00"
ATTRS{bDeviceProtocol}=="00"
ATTRS{devpath}=="2"
ATTRS{idVendor}=="0403"
ATTRS{speed}=="12"
ATTRS{bNumInterfaces}==" 1"
ATTRS{bConfigurationValue}=="1"
ATTRS{bMaxPacketSize0}=="8"
ATTRS{busnum}=="3"
ATTRS{devnum}=="22"
ATTRS{configuration}==""
ATTRS{bMaxPower}=="90mA"
ATTRS{authorized}=="1"
ATTRS{bmAttributes}=="80"
ATTRS{bNumConfigurations}=="1"
ATTRS{maxchild}=="0"
ATTRS{bcdDevice}=="0400"
ATTRS{avoid_reset_quirk}=="0"
ATTRS{quirks}=="0x0"
ATTRS{version}==" 1.10"
ATTRS{urbnum}=="11"
ATTRS{ltm_capable}=="no"
ATTRS{manufacturer}=="FTDI"
ATTRS{removable}=="removable"
ATTRS{idProduct}=="6001"
ATTRS{bDeviceClass}=="00"
ATTRS{product}=="USB <-> Serial"
looking at parent device '/devices/pci0000:00/0000:00:14.0/usb3':
KERNELS=="usb3"
SUBSYSTEMS=="usb"
DRIVERS=="usb"
ATTRS{bDeviceSubClass}=="00"
ATTRS{bDeviceProtocol}=="01"
ATTRS{devpath}=="0"
ATTRS{idVendor}=="1d6b"
ATTRS{speed}=="480"
ATTRS{bNumInterfaces}==" 1"
ATTRS{bConfigurationValue}=="1"
ATTRS{bMaxPacketSize0}=="64"
ATTRS{authorized_default}=="1"
ATTRS{busnum}=="3"
ATTRS{devnum}=="1"
ATTRS{configuration}==""
ATTRS{bMaxPower}=="0mA"
ATTRS{authorized}=="1"
ATTRS{bmAttributes}=="e0"
ATTRS{bNumConfigurations}=="1"
ATTRS{maxchild}=="4"
ATTRS{bcdDevice}=="0313"
ATTRS{avoid_reset_quirk}=="0"
ATTRS{quirks}=="0x0"
ATTRS{serial}=="0000:00:14.0"
ATTRS{version}==" 2.00"
ATTRS{urbnum}=="383"
ATTRS{ltm_capable}=="no"
ATTRS{manufacturer}=="Linux 3.13.0-32-generic xhci_hcd"
ATTRS{removable}=="unknown"
ATTRS{idProduct}=="0002"
ATTRS{bDeviceClass}=="09"
ATTRS{product}=="xHCI Host Controller"
looking at parent device '/devices/pci0000:00/0000:00:14.0':
KERNELS=="0000:00:14.0"
SUBSYSTEMS=="pci"
DRIVERS=="xhci_hcd"
ATTRS{irq}=="40"
ATTRS{subsystem_vendor}=="0x17aa"
ATTRS{broken_parity_status}=="0"
ATTRS{class}=="0x0c0330"
ATTRS{enabled}=="1"
ATTRS{consistent_dma_mask_bits}=="64"
ATTRS{dma_mask_bits}=="64"
ATTRS{local_cpus}=="ff"
ATTRS{device}=="0x1e31"
ATTRS{msi_bus}==""
ATTRS{local_cpulist}=="0-7"
ATTRS{vendor}=="0x8086"
ATTRS{subsystem_device}=="0x3977"
ATTRS{d3cold_allowed}=="1"
looking at parent device '/devices/pci0000:00':
KERNELS=="pci0000:00"
SUBSYSTEMS==""
DRIVERS==""
I tried implementing the first solution @ How to distinguish between identical USB-to-serial adapters? by assigning KERNELS=="3-1"
to ttyUSB0 and KERNELS=="3-2"
to ttyUSB1, but it is not persistent and changes everytime I re-connect the devices. Moreover ATTRS{devnum}
also keeps changing everytime, but it can be noted that they are always in sequence. So, can I use them to fix device names? I am not sure that same device will always be initialized with smaller or larger devnum.
Another option that I tried after following How to lock device id's to port addresses?, and did:
udevadm info /dev/ttyUSB0
P: /devices/pci0000:00/0000:00:14.0/usb3/3-1/3-1:1.0/ttyUSB0/tty/ttyUSB0
N: ttyUSB0
S: serial/by-id/usb-FTDI_USB__-__Serial-if00-port0
S: serial/by-path/pci-0000:00:14.0-usb-0:1:1.0-port0
E: DEVLINKS=/dev/serial/by-id/usb-FTDI_USB__-__Serial-if00-port0 /dev/serial/by-path/pci-0000:00:14.0-usb-0:1:1.0-port0
E: DEVNAME=/dev/ttyUSB0
E: DEVPATH=/devices/pci0000:00/0000:00:14.0/usb3/3-1/3-1:1.0/ttyUSB0/tty/ttyUSB0
E: ID_BUS=usb
E: ID_MM_CANDIDATE=1
E: ID_MODEL=USB__-__Serial
E: ID_MODEL_ENC=USB\x20\x3c-\x3e\x20Serial
E: ID_MODEL_FROM_DATABASE=FT232 USB-Serial (UART) IC
E: ID_MODEL_ID=6001
E: ID_PATH=pci-0000:00:14.0-usb-0:1:1.0
E: ID_PATH_TAG=pci-0000_00_14_0-usb-0_1_1_0
E: ID_REVISION=0400
E: ID_SERIAL=FTDI_USB__-__Serial
E: ID_TYPE=generic
E: ID_USB_DRIVER=ftdi_sio
E: ID_USB_INTERFACES=:ffffff:
E: ID_USB_INTERFACE_NUM=00
E: ID_VENDOR=FTDI
E: ID_VENDOR_ENC=FTDI
E: ID_VENDOR_FROM_DATABASE=Future Technology Devices International, Ltd
E: ID_VENDOR_ID=0403
E: MAJOR=188
E: MINOR=0
E: SUBSYSTEM=tty
E: USEC_INITIALIZED=8719192
and then:
udevadm info /dev/ttyUSB1
P: /devices/pci0000:00/0000:00:14.0/usb3/3-2/3-2:1.0/ttyUSB1/tty/ttyUSB1
N: ttyUSB1
S: serial/by-id/usb-FTDI_USB__-__Serial-if00-port0
S: serial/by-path/pci-0000:00:14.0-usb-0:2:1.0-port0
E: DEVLINKS=/dev/serial/by-id/usb-FTDI_USB__-__Serial-if00-port0 /dev/serial/by-path/pci-0000:00:14.0-usb-0:2:1.0-port0
E: DEVNAME=/dev/ttyUSB1
E: DEVPATH=/devices/pci0000:00/0000:00:14.0/usb3/3-2/3-2:1.0/ttyUSB1/tty/ttyUSB1
E: ID_BUS=usb
E: ID_MM_CANDIDATE=1
E: ID_MODEL=USB__-__Serial
E: ID_MODEL_ENC=USB\x20\x3c-\x3e\x20Serial
E: ID_MODEL_FROM_DATABASE=FT232 USB-Serial (UART) IC
E: ID_MODEL_ID=6001
E: ID_PATH=pci-0000:00:14.0-usb-0:2:1.0
E: ID_PATH_TAG=pci-0000_00_14_0-usb-0_2_1_0
E: ID_REVISION=0400
E: ID_SERIAL=FTDI_USB__-__Serial
E: ID_TYPE=generic
E: ID_USB_DRIVER=ftdi_sio
E: ID_USB_INTERFACES=:ffffff:
E: ID_USB_INTERFACE_NUM=00
E: ID_VENDOR=FTDI
E: ID_VENDOR_ENC=FTDI
E: ID_VENDOR_FROM_DATABASE=Future Technology Devices International, Ltd
E: ID_VENDOR_ID=0403
E: MAJOR=188
E: MINOR=1
E: SUBSYSTEM=tty
E: USEC_INITIALIZED=79099407
and then wrote udev rule in the file as 44-my-devices.rules located at /etc/udev/rules.d/:
SUBSYSTEM=="tty", ENV{ID_PATH}=="pci-0000:00:14.0-usb-0:1:1.0", SYMLINK+="ttyUSBMotor1"
SUBSYSTEM=="tty", ENV{ID_PATH}=="pci-0000:00:14.0-usb-0:2:1.0", SYMLINK+="ttyUSBMotor2"
I also copied it to /lib/udev/rules.d/ and then reloaded the rules as:
sudo udevadm control --reload-rules
sudo /etc/init.d/udev restart
But nothing did happen. I think I am making some mistake here, as this should work. The hardware associated always remains the same, and the rule must work. I have tried restarting the pc as well, but to no effect.
S: serial/by-path/pci-0000:00:14.0-usb-0:2:1.0-port0
differs fromS: serial/by-path/pci-0000:00:14.0-usb-0:1:1.0-port0
. You could use that to differentiate, assuming it doesn't change.ENV{ID_PATH}
for both of them in udev rules, as I have updated in answer.