Re: pl2303 Serial/USB problem - /dev/ttyUSB0 not created

On Fri, 06 Aug 2010 14:02:11 +0100
Barry Samuels <barry@xxxxxxxxxxxxxxxxxxxxx> wrote:

Desktop and Laptop both have Debian Testing installed and up to date; both
with self-compiled kernel 2.6.32.

I have a CurrentCost electricity usage monitor which is normally connected
to my desktop via USB and is working properly. When the unit is plugged in
I get a number of lines in syslog like so:

kernel: usb 4-1: new full speed USB device using uhci_hcd and address 12
kernel: pl2303 4-1:1.0: pl2303 converter detected
kernel: usb 4-1: pl2303 converter now attached to ttyUSB0

I am trying to get this same device working on my laptop but this time I
see the following in syslog:

kernel: pl2303: Prolific PL2303 USB to serial adaptor driver

but nothing else i.e no 'attached to ttyUSB0'. Looking in /dev there is no

Whereas the desktop also loads the pl2303 and usbserial kernel modules
automatically when the device is connected the laptop does not and when I
load them manually I get only the above mentioned line in syslog.

When the USB device is plugged in there is apparently no reaction from the
operating system on the laptop when watching /var/syslog using 'tail'.
That, I think, is the main problem. Other USB devices on the laptop do

Needless to say the software which monitors the device won't connect.

Any suggestions please?

Are you using the *exact* same kernel on both systems? Do you have the
same problem with a Debian stock kernel? [The first step when
debugging problems with self-compiled kernels is always to check if the
problem exists with stock kernels, or only with one's own.[

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