(E-Mail Removed) (John) wrote:
>hi,
>I have an IBM thinkpad (A31) and I am trying to use a null-modem
>serial cable to connect it to my Desktop. My desktop is running WinXP
>and my Laptop dual boots WinXP and Linux (Red-Hat 9). When I boot the
>laptop in WinXP and I connect the cable to the serial ports everything
>works fine (in hyperterminal). I think boot in to Linux and try to use
>minicom to communicate to the XP machine. Nothing going. I've tryed
>playing with all the configuration options but to no avail! I can't
>even find out which serial port (dev/ttyS?) is linux registering my
>COM port. serialstat doesn't work (complains about some error)
>
>I've tried all the ports in minicom but not even a single charcter is
>transferred.
>
>Can anyone help?
The best approach is to solve each problem one step at a time.
Follow the below suggestions as closely as you can. If you get
stuck, post what you did, post the results. For example, don't
tell us that you ran proggie xyz and got "some error". Cut
and paste the actual error message into your article. Somebody
will recognize your problem, and give you exact instructions on
what to do next.
Anyway, here's what to do now:
Try using setserial if your system has it, to tell you how your
serial ports are configure. You should get something like this:
>/sbin/setserial -a /dev/ttyS0
/dev/ttyS0, Line 0, UART: 16550A, Port: 0x03f8, IRQ: 4
Baud_base: 115200, close_delay: 50, divisor: 0
closing_wait: 3000
Flags: spd_normal skip_test
Note that the UART, the Port, and the IRQ are all reasonable
values. For an unequipped port, something like this will
be shown:
>/sbin/setserial -a /dev/ttyS2
/dev/ttyS2, Line 2, UART: unknown, Port: 0x03e8, IRQ: 4
Baud_base: 115200, close_delay: 50, divisor: 0
closing_wait: 3000
Flags: spd_normal skip_test
The only hint is the UART listed as "unknown", which basically
means nothing responded in an expected manner (because there isn't
anything there to respond, in this case).
If that doesn't point it out immediately, find a modem and
serial cable that are known to work, and hook them to the serial
port on your laptop. That gives you something that *will*
respond when you access it.
If you have more than one device special file that indicates a
possibly valid serial port, there are a few tricks that might
tell you port talks to the modem. If the modem has lights that
in some why tell you when it is doing a reset (old SupraFAX
modems, for example, have a two digit lcd display, and if the
modem is sent ATZ ever pixel on the display lights up for about
1 second), you can try doing this:
>echo -e "ATZ\r\n" > /dev/ttyS0
to see if that causes the modem to indicate it has been reset.
If not, change that to /dev/ttyS1 and see what happens.
If the modem can't help you, use minicom to try talking to it.
However, be aware that minicom can trick you, and cause great
confusion. If you try changing the settings for minicom it will
appear to change them, but won't unless you do it exactly right.
1) su to root.
2) invoke "minicom -s".
3) set the serial port to ttyS1 or whatever.
4) save the settings to either default, or
to some named configuration, such as "port1".
5) exit minicom.
6) exit root.
7) invoke minicom, as "minicom" to get the default config,
or as "minicom port1" to get the port1 configuration.
Otherwise, it will say ttyS1, but you won't get a response
because the modem actually is on ttyS1 but minicom is lying
to you and is still talking to ttyS0.
--
Floyd L. Davidson <http://web.newsguy.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska)
(E-Mail Removed)
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