prp
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As There Is No Firmware Conference, A Couple of Questions Here
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Apr 8 16:53 UTC 1999 |
AT commands for Modems
Although I can't find it now, I do remember somebody, somewhere on Grex
looking for information on these. So am I. It seems I have a new modem
and old manual. Anyone have a copy of the compleat command set and
register values? It turns out that the commands "ATV1" and "ATX1" help,
but I have no idea what the really do.
An original IBM AT
Sometimes when rebooting, it sends the message "SSS" in Morse Code.
Anybody know what this means? Anybody have a copy of the Technical
Reference?
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scg
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response 3 of 7:
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Apr 9 07:24 UTC 1999 |
atx0 tells the modem I have that has trouble correctly noticing a dial tone
to ignore the lack of dial tone and dial anyway. atx1 would, I believe, tell
it to once again pay attention to whether it has a dial tone. Your modem may
varry, of course.
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rtg
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response 4 of 7:
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Apr 10 04:42 UTC 1999 |
The 'AT' command set varies from modem to modem, about like terminal
control codes varying between the multitude of VT-100 clones and emulators
out there. YMMV!
The older commands (A thru Z) are commonly supported. When you get into
the world of s-registers, &A, +A, %A, etc., You're dreaming unless you've
got the exact manual.
After that disclaimer, My USR modem recognizes the folowing:
V0 - Enable numeric response mode
V1 - Enable text(english) response mode
X - Extended response codes. (Wide variation here between manufacturers,
but in general, the higher the number, the more detail on call-progress
and protocol negotiation it will tell you)
X0 - Ignore network tones and omit connection speed message.
X1 - Enable connection speed result codes
X2 - Enable detection of dial tone.
X3 - Enable detection of busy tone.
X4 - Enable detection of busy and dial tones (factory default on my modem)
X5 - Report ringing, but dial tone is ignored.
X6 - Use adaptive dialing (automatically determine whether DTMF or pulse
is required)
As long as we're on this theme, you might be interested in:
W0 - Report the DTE speed on the CONNECT message
W1 - Report the line speed, error-correcting protocol, and DTE speed.
W2 - Report the DCE speed (line carrier) on the CONNECT message.
As a side note, modern modems all have buffers, which allow the DTE speed
between the computer serial port and the modem, to run faster than the DCE
speed, or carrier speed on the phone line. Most modems I've seen report
the DTE speed as the default on the CONNECT message, so the users are
lulled into thinking they've gotten their money's worth for their new
'56k' modem, while Ameritech's old copper can barely support 14.4k in some
areas. I put a W1 in my initialization string, and I've saved myself the
expense of an upgrade that wouldn't gain me anything!
If you've got a 28.8 or 33.6 modem, and you're thinking of accelerating to
56k, stop and think. Call USR's BBS at 1-847-262-6000 and log in with
first name - 'line' and last name - 'test'. It'll tell you if your phone
line is even capable of 56k connections. It's a long distance call, but
the test only takes a minute or so.
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