Re: minicom serial output

From: Floyd L. Davidson (
Date: 07/21/04

Date: Wed, 21 Jul 2004 05:58:42 -0800

anonymous coward <anonymous.coward@nospam.nowhere> wrote:
  [background info snipped]
>I've been trying to get them to work using minicom. I've set the correct
>data rate, flow control settings etc. etc. but minicom only seems to work
>in one direction. It will print data from my electronics, but it will
>not echo what I type into the keyboard into my electronics.
>If I try to start a modem, my electronics reacts to the control sequences
>so there does not seem to be any hardware problem.
>Any ideas? I'm sure I'm doing something pretty basic wrong, but I have no
>idea what...

I'm not sure that I understand your description. Are you saying
that when you type something on the keyboard, the device you
have connected to the serial port *does* react? Meaning that it
has received the data?

If that is correct, you have two possible options. As another
poster said, you set minicom for "local echo". The preferred
method, however, is to configure your remote device to echo! Of
course, it might not have that capability. (And it might be that
it already is configured that way, but has been confused by the
modem init string that minicom automatically sends at startup.)

So "I try to start a modem" means that you used minicom's
"Initialize Modem" command and it sent something the device
responded to... you want to configure minicom to *not* send it!

Configuring minicom can also be a little confusing, because it
will often appear to have done something when in fact it has
not. Setting the serial port parameters is one of those issues.
So it is also possible that you are not actually getting the
port configured. If you are changing the settings each time,
that is probably true, and all your device is getting is garble.

Here is the proceedure you need to follow to properly setup the
serial port. You can also change the modem init string at the
same time.

   1) su to root.

   2) Invoke "minicom -s".

   3) Get the "configuration" menu by typing in
       two characters, ^A and then O.

   4) Position the highlight on the menu list by
       using the up or down arrow keys and type a
       <RETURN> to select an option to configure.

   5) You may not need to change anything in the
       first two areas listed, "Filenames and path"
       and "File transfer protocols". But look at
       them to see what options are available, for
       future reference. You do want to set the
       appropriate entries in "Serial port setup"
       and in "Modem and dialing" where at least
       you want to delete all of the modem init
       strings to avoid sending them at start up.
       "Screen and keyboard" probably do not need
       any changes.

   6) Save the settings to either default, or
       to some named configuration, such as "port1"
       or perhaps use the device's name.

   7) Exit minicom.

   8) Exit root.

   9) Invoke minicom, as "minicom" to get the
       default config, or as "minicom port1" to get
       the port1 configuration.

It is probably not a good idea to save your configuration as the
default, which perhaps should always be a "modem" type of setup.
Any radical change should be to a named config file.

FloydL. Davidson           <>
Ukpeagvik (Barrow, Alaska)