Re: Can't Query External Serial Modem

From: "Tommy Trussell" <tommy.trussell@xxxxxxxxx>
Reply-To: "Ubuntu user technical support,not for general discussions"
To: "Ubuntu user technical support,not for general discussions"
Subject: Re: Can't Query External Serial Modem
Date: Mon, 12 Mar 2007 20:02:15 -0500

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.

I should clarify - HyperTerminal doesn't cause the lights to respond,
wvdialconf does. And minicom sends the lights flashing maybe 1 time in

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