Thanks for the reply.I have read various HowTos and will try them out
shortly.
However, this is only a partial solution. It depends on having USB-
serial adapters from different manufacturers. At work, I have FOUR USB-
serial adapters, all made by Bafo, connected to the following devices:
* a development project, talking to Uboot or a Linux console
* a development project, talking some variant of gdb to a low-level debug server
* a Tektronix oscilloscope, for getting screenshots
* a GPS receiver
Looking at the manufacturer alone does not work here: I would have to
look at a serial number. However, the output of udevinfo -a -p
/class/tty/ttyUSB0 does not give a serial number. There is no evidence
of a serial number from lsusb -v, or in syslog.
Questions:
1. Does the PL2303 device include a serial number? The PL2303 chip supports an
EEPROM, but who knows whether BAFO included one in their product.
2. Who is responsible for reading the USB serial number: the USB subsystem in
general, the USB class driver, or the PL2303 driver?
3. udevinfo -a -p /class/tty/ttyUSB0 does not give a serial number
I can accept that this is not a bug in the kernel. If the USB serial-
class specification does not MANDATE a serial number, then there is a
bug in the specification, and there is no general solution. If the USB
serial-class driver does not read the serial number, then there is a
problem at that level. If the PL2303 driver does not read the serial
number, then there is a problem with the PL2303 driver. If the Bafo
serial adapter does not include a serial number, then I will buy a
serial adapter that does (does anybody know of one?)
However, there is still a bug in Ubuntu at a user-interface level. A
normal user does not want to go writing udev rules to ensure that the
modem is always named /dev/modem, the weather-station is /dev/weather-
station, and the GPS unit is /dev/gps. I would like to see a GUI of some
sort that displays a list of all 'connectable' ports (serial ports, USB
serial ports, parallel ports, etc) along with sufficient data to
identify them uniquely (including serial number), and allow the user to
specify an application-level device such as /dev/modem, and create the
appropriate udev rule. Or perhaps he will paint each USB serial adapter
a different colour, then create devices such as /dev/ttyUSB-blue and
/dev/ttyUSB-red, using the serial number provided by the GUI. He can
then create further links like this
/dev/gps -> /dev/ttyUSB-blue -> /dev/ttyUSB0, where the first
/dev/wx -> /dev/ttyUSB-red -> /dev/ttyUSB1
This should probably be a new specification not a bug report.
Here is partial output of lsusb -v, showing that there is no serial number.
Perhaps this should be a separate bug report.
Bus 004 Device 002: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 1.10
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 8
idVendor 0x067b Prolific Technology, Inc.
idProduct 0x2303 PL2303 Serial Port
bcdDevice 2.02
iManufacturer 0
iProduct 0
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 39
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xa0
(Bus Powered)
Remote Wakeup
MaxPower 100mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 3
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 0
bInterfaceProtocol 0
iInterface 0
--
Two USB serial adapters get different /dev/ttyUSBn names after reboot
https://bugs.launchpad.net/bugs/107208
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