CentOS - Feb 2016 - USB Serial ports (ttyACMn) CentOS 6.7 (64-bit) vs. CentOS 6.7 (64-bit)

I have not yet found a USB-to-serial adapter detected as /dev/ttyACM1.
Try /dev/ttyUSB0 ?

- Mike

On Sat, Feb 13, 2016 at 10:14 AM, Robert Heller <heller at deepsoft.com>
wrote:
> I sent this out about a week or so ago, but I have heard nothing. I am
> *thinking* it is a SELINUX problem, but I cannot figure out what. The
> SELINUX
> settings for both machines are *exactly* the same (the stock defaults for a
> standard CentOS 6 install).  The *only* difference is that the desktop
> (sauron) has a few VMs setup (under KVM) and the laptop (gollum) does not.
> The
> desktop has an AMD processor and a nVidia video chipset and the laptop has
> an
> Intel processor and an Intel graphic controller.  Although I can't see
how
> either the processor or video chipset would have anything to to with the
> USB
> or USB serial port-type devices.  The desktop also has a PCI quad serial
> port
> card and includes the 8250.nr_uarts=8 kernel option and is set up to use an
> analog dialup modem to make PPP connections (again, I don't see that as
> having
> anything to do with anything).
>
> Both machines are running the same kernel: 2.6.32-573.12.1.el6.x86_64
>
>
>
>
> At Thu, 4 Feb 2016 16:13:33 -0500 Robert Heller <heller at
deepsoft.com>
> wrote:
>
> >
> > I have two computers: both running CentOS 6.7, 64-bit, with
> > kernel 2.6.32-573.12.1.el6.x86_64.  One is a laptop with an 2 core
Intel
> > processor and the other is a desktop machine with a 4 core AMD
> processor. Both
> > with selinux enabled.
> >
> > I have a USB serial port device (a RR-CirKits LCC-Buffer USB).  On the
> desktop
> > I am getting this error:
> >
> > sauron.deepsoft.com% sudo minicom
> > Device /dev/ttyACM0 access failed: No such file or directory.
> > sauron.deepsoft.com% dir -lZ /dev/ttyACM0
> > crw-rw----. root dialout system_u:object_r:tty_device_t:s0
/dev/ttyACM0
> >
> > But it is working on the laptop!
> >
> > gollum.deepsoft.com% dir -lZ /dev/ttyACM1
> > crw-rw----. root dialout system_u:object_r:tty_device_t:s0
/dev/ttyACM1
> >
> > Same kernel, same device (except it is showing up as ttyACM1 on the
> laptop).
> >
> > What is going on here?
> >
> >
> >
>
> --
> Robert Heller             -- 978-544-6933
> Deepwoods Software        -- Custom Software Services
> http://www.deepsoft.com/  -- Linux Administration Services
> heller at deepsoft.com       -- Webhosting Services
>
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>


-- 
---~~.~~---
Mike
//  SilverTip257  //

On Feb 15, 2016, at 10:34 AM, Mike - st257 <silvertip257 at gmail.com>
wrote:
> 
> I have not yet found a USB-to-serial adapter detected as /dev/ttyACM1.
> Try /dev/ttyUSB0 ?
Both naming schemes are correct, depending on the *type* of USB to serial
converter.  The difference comes down to a low-level USB implementation detail
which I?ve never bothered to commit to long-term memory.

I just say ?dmesg | tail? or ?ls -ltr /dev? shortly after plugging the device
in.  One of the two tells me which scheme that particular device uses.

On Mon, Feb 15, 2016 at 6:52 PM, Warren Young <wyml at etr-usa.com> wrote:
> On Feb 15, 2016, at 10:34 AM, Mike - st257 <silvertip257 at
gmail.com> wrote:
> >
> > I have not yet found a USB-to-serial adapter detected as /dev/ttyACM1.
> > Try /dev/ttyUSB0 ?
>
> Both naming schemes are correct, depending on the *type* of USB to serial
> converter.  The difference comes down to a low-level USB implementation
> detail which I?ve never bothered to commit to long-term memory.
>
Yep.
If I recall correctly, minicom defaults to ttyACM0 or 1 on a fresh install.
I wasn't claiming that device name was wrong, but more so that ttyUSB0 is
more common (though that may not truly be the case).

>
> I just say ?dmesg | tail? or ?ls -ltr /dev? shortly after plugging the
> device in.  One of the two tells me which scheme that particular device
> uses.

Yes indeed. Dmesg is my first stop as well. :-)

This could suffice as well. Many ways to "skin the cat"
~$ ls -l /dev/tty[A-Z]*

-- 
---~~.~~---
Mike
//  SilverTip257  //