Minicom - data is corrupted between two PC's ??

[David Timms]

David Timms wrote:
> Erik Grootjans wrote:
>> ----- Original Message ----- From: "Mikkel L. Ellertson" 
>> <mikkel at infinity-ltd.com>
>> To: "For users of Fedora" <fedora-list at redhat.com>
>> Sent: Wednesday, March 28, 2007 8:24 PM
>> Subject: Re: Minicom cant get info from /dev/ttyS0 and ttyS1
>>
>>
>>> Erik Grootjans wrote:
>>>> Thanks
>>>>
>>>> But i m only in the first stage --> configuring as root
>>>> and at this moment even that does not work.
>>>> (as root im owner of the device - so rights must not be a problem, i
>>>> guess
>>>>
>>>> The next step is then to get it working as an user.
>>>>
>>>> Erik
>>>>
>>> Dumb question - did you clear out the modem init string and set
>>> "Modem has DCD line" to no? You can use the -o option when starting
>>> minicom to skip the modem initialization.
>>>
>>> I normally set up one profile with empty modem strings, and DCD
>>> turned off for uses like this.
>  > I didn't, but i started minicom with -o -s, to setup, and then changed
>  > to the correct values. And also after a restart of the router, i did get
>  > no communication.
>  >
>  > I checked to clear al fields in modem setup from A-L and changed DCD
>  > line to NO.
>  > I did save it to console.
>  > restart the router --> nothing
>  > restart minicom -o console (=saved config) --> nothing
>  > restart minicom -o console + sometime latere restart router --> nothing
>  > restart router + start minicom -o console --> nothing
>  >
>  > So this seems to make no difference, too bad.
> Posters:
> Thanks for all the tips on serial comms with minicom.
> 
> Once I checked all the above, one computer can start minicom fine, but 
> the computer {a hp nx6320 notebook} was having:
> Device /dev/ttyS0 lock failed: Operation not permitted.
> 
> It seems if I attempt to start minicom from a user account, then the 
> lock file is generated in /var/lock/*tty* , but then has some problem.
> su to root and running minicom after this shows identical error.
> rm the lock file and running minicom from root is then successful.
> 
> However, with a 3-wire crossover between the two PC's at 115200 8n1 just 
> junk chars were coming up on the other computer in one direction and 
> nothing in the opposite. After a time (20s), suddenly junk also appeared 
> on the other computer (not the letters typed but >ascii chars}
> 
> I reset to 38400 and 9600. result now is one direction characters come 
> out normal, and in the other direction I see weird characters:
> ?...?p??.?? . . ? ?. ?  ? ? ?   ? . ?? ? ?   .???.??    .???.
> +++++++++?+#++?++++?+#+?++_++?+??+?_?+_?.......................+++
> 
> I'm going to find my DB9F plug with a 2-3 short in it later today to 
> test each end separately.
> 
> It appears that the data rates are mismatched, yet the status text says 
> 9600 8N1 on both machines.
> Any hints for resolving this one ?
I also set the Modem reset string to '', save the dfl and restarted both 
minicoms. Now they are talking normally at 9600 n81. And changing live 
to 115200, and save dfl, and they immiediately communicate properly. Any 
ideas on what's going wrong here ?

  I had a suspicion that selinux might be getting in the way for normal 
user access. # setenforce 0 then running $ minicom then works OK.

Changing back to setenforce 1 stops it working {lock file permissions}.

Any selinux experts here ?

Also, in var/log/messages, I see mgetty having a little hernia every 45secs:
: init chat failed, exiting...: Interrupted system call
: failed in mg_init_data, dev=ttyS0
I have a ppp dialup connection configured, but inactive.

Any help much appreciated, thanks

DaveT.