Can't Query External Serial Modem

Tommy Trussell tommy.trussell at
Tue Mar 13 01:02:15 UTC 2007

On 3/12/07, Bernard Helyer <b.helyer at> wrote:
> So I sucked it up and bought a serial modem. I in fact have two; on is an
> old 14k one that was given to me, and the one I bought was a 56k 'Elsa
> MicroLink Fun Modem'. My problem is, neither Windows nor Ubuntu can query it
> (HyperTerminal in Windows, and Minicom in Linux, neither will respond to an
> AT command). If I run '$ sudo wvdialconf /etc/wvdial.conf' the lights flash
> on both modems, however wvdialconf responds that it can't find a modem, and
> have I configured it properly with setserial.

I recommend going back to minicom (or HyperTerminal if you must) and
try several different serial settings. For most similar serial devices
I would expect 115200 - 8N1 to work. (That's 115200 bits per second, 8
bits, no parity, 1 stop bit. In minicom there's a shortcut option to
set the 8N1.)

First I would try downgrading the speed to 57600 bps, then maybe down
even to 19200 if that doesn't work. In between speed changes you can
try powering down the modem. You should normally see an OK when you
type AT <enter> -- but be sure to give it about a 3 second pause
before typing the next attempt. Since you're certain the lights are
blinking in response to what you're typing, it's possible the modem
firmware is set to not respond, but you should get a dialtone and
dialing sounds when you type ATDT11111 or something like that.

OH and of course some modems sense the state of the phone line, so
plug a telephone into the auxiliary port and make sure the connection
is good through the modem.

If none of that has the effect you expect I would next suspect that
the serial cable is wired for another type of device (something other
than a modem).

But diagnosing serial devices is somewhat of a "black art." Let me
know what you discover.

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