Serial Port HowTo (Cannot open /dev/ttyS0)

chun-mee · 07-08-2006, 10:24 AM

Hi!

My problem is that I have no idea how to make the device actually installed in the serial port actually appear on and be used by the system.

What I need to achieve is to get scmxx to talk to my Siemens ME45 mobile phone using the datacable first (and then IrDA, but that will be another thread). The cable, the phone and the serial port are known to be working (under Windows).

I recently installed Kanotix, which I totally unfamiliar with (2.6.14-kanotix-9), and scmxx returns this message

root@KanotixBox:~# scmxx --info
Using "ANSI_X3.4-1968" as system character set.
Accessing device /dev/ttyS0...
Error: No such file or directory

Error: Cannot open /dev/ttyS0

I type dmesg and there is no sign of the phone that I connect anywhere.

I am using USB palm pda in a similar manner and I have to specify the port manually, but for that device I press hotsync first and then it creates the port so I can see it by typing dmesg, but this phone does not have a hotsync button so how to talk to it usign scmxx?

My feeling is that this could apply to any similar device, and that my problem is that I have no idea how to check if the device is attached to the serial port, or how to talk to it.

Thank you in advance for all the help!

Brian1 · 07-08-2006, 10:51 AM

Lets check a few things first.
Are you using com1 on the windows side to communicate?
If so then usually it will be /dev/ttyS0

To see if it exist use the command ' ls -la /dev/ttyS* ' and post output.
If get something like this

Code:

[crusher58@lcomp58 ~]$ ls -la /dev/ttyS*
crw-rw----  1 root uucp 4, 64 Jul  8 05:36 /dev/ttyS0
crw-rw----  1 root uucp 4, 65 Jul  8 05:36 /dev/ttyS1
crw-rw----  1 root uucp 4, 66 Jul  8 05:36 /dev/ttyS2
crw-rw----  1 root uucp 4, 67 Jul  8 05:36 /dev/ttyS3

Then root owns the device and lets no one else to use it. This is a permissions issue.
To fix use the command login as root ' su ' and issue the command ' /sbin/chmod 666 /dev/ttyS0 '.
Now you get the following for ttyS0

Code:

[crusher58@lcomp58 ~]$ ls -la /dev/ttyS*
crw-rw-rw-  1 root uucp 4, 64 Jul  8 05:36 /dev/ttyS0

Now try connecting.

Brian1

chun-mee · 07-14-2006, 06:35 PM

To see if it exist use the command ' ls -la /dev/ttyS* ' and post output.
If get something like this

Code:

[crusher58@lcomp58 ~]$ ls -la /dev/ttyS*
crw-rw----  1 root uucp 4, 64 Jul  8 05:36 /dev/ttyS0
crw-rw----  1 root uucp 4, 65 Jul  8 05:36 /dev/ttyS1
crw-rw----  1 root uucp 4, 66 Jul  8 05:36 /dev/ttyS2
crw-rw----  1 root uucp 4, 67 Jul  8 05:36 /dev/ttyS3

Hey, Brian, thank you for helping!

I do that, but:

Code:

root@KanotixBox:~# ls -la /dev/ttyS*
ls: /dev/ttyS*: No such file or directory

What next?
Thanks!