Re: Fwd: Serial Port Issues

["Martin McCormick" <martin.m@suddenlink.net>]

deloptes <deloptes@gmail.com> writes:
> Chris Rhodin wrote:
> 
> > Tonight I'll look at the serial port ioctls and see if I can spot a
> > difference there.  I also try enabling flow control and fiddling with 
> the
> > signals to see if that unstops it.
> 
> Are you sure that this is enabled in the BIOS, also some serial ports like
> HP have special connectors and layouts.
> Best would be to look at the manual first.
> 
> I have attached a USB to the server. From there I can log in to the
> firewall. I can not use the same port in the opposite direction.
> 
> However it is strange that you do get the connection only in one 
> direction.
> It could be some kind of special connector
> 
> Otherwise I used those to enable the service
> 
> https://wiki.debian.org/systemd#Virtual_and_serial_console_changes
> 
> https://www.thegeekdiary.com/centos-rhel-7-how-to-configure-serial-getty-with-systemd/
> https://wiki.archlinux.org/index.php/Working_with_the_serial_console

	Another possible fly in the ointment could be a hardware
issue.  Some RS-232 ports are old-school and aren't happy with
any voltage range other than +12 for one state and -12 for the
other while there are serial ports that can handle state changes
of + or - 3 volts so they safely handle logic-level signals and
also can handle the old-school RS-232 levels.  Then there are
some that handle logic-level signals and would figuratively melt
if you hit them with +-12 volts.

Martin