ewhac@well.UUCP (02/18/87)
[ NO CARRIER ]
Whether or not this question has been beaten into the dirt before, I
don't know, as I haven't paid much attention to this group (when 50% of the
subject lines say "2400 baud modems," you tend to start ignoring a lot of
things). So here goes.
I have a MultiTech 224E error correcting modem. It's got automatic
fallback, both flavors of Hayes compatability, etc. It also has MNP error
correction in hardware.
The manual states that, if I issue a certain command (AT&E1), the
modem will automatically do handshaking upon connection to determine if the
modem on the other end knows what to do with MNP, and if so, connect with
MNP. Otherwise, it will connect normally.
I've been having trouble with this. When I call up some local
non-MNP modems in Auto-Reliable mode (as the manual calls it), I get
garbage, as though the modem I'm calling is running at the wrong baud rate.
Sometimes (rarely), this doesn't happen, and I get a good connection (with a
non-MNP modem (by the way, I've never connected with an MNP modem)).
Am I doing something wrong, or is the act of MNP handshaking causing
the destination modem to see a framing error, which many systems interpret
as a signal to change baud rates?
Help! I'd like to be able to use MNP whenever possible.
ADV-thanks-ANCE.
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Recumbent Bikes: "Work FOR? I don't work FOR
The _O_n_l_y Way To Fly! anybody! I'm just having fun."zemon@felix.UUCP (02/20/87)
In article <2607@well.UUCP> ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab) writes: > I've been having trouble with this. When I call up some local >non-MNP modems in Auto-Reliable mode (as the manual calls it), I get >garbage, as though the modem I'm calling is running at the wrong baud rate. >Sometimes (rarely), this doesn't happen, and I get a good connection (with a >non-MNP modem (by the way, I've never connected with an MNP modem)). That could be because the system behind the modem you are calling is running at the wrong baud rate. I have the same problem and here is what causes it: 1) your modem (A) calls another modem (B) 2) B whistles "hello -- I talk XXXX baud" 3) A whistles "hello -- I talk that speed, too" 4) B settles down and gets ready to interpret whistles as data and pass it along to its host computer 5) A whistles "oh yeah -- Do you talk MNP?" 6) B turns A's last whistle into bytes of data and sends the bytes along to its host computer 7) B's host computer sees "random" data and assumes it is at the wrong baud rate, so it changes to another (300 baud, perhaps) 8) A doesn't hear any response so it assumes B cannot talk MNP 9) A settles down to turn data into whistles and tells you "CONNECT" or some such message 10) you type <CR> and get garbage back from B's very confused host The only solution I have thought of is to persuade B to buy a better modem. That's not very easy when B == Western Union EasyLink. Soooooo, one of my Racal-Vadic 2400 baud modems is set to never use MNP. Sigh. If you want to try connecting to an MNP modem, send me mail. We can set up a UUCP link or something. -- -- Art Zemon FileNet Corporation Costa Mesa, California ...!hplabs!felix!zemon
naftoli@aecom.UUCP (02/20/87)
In article <2607@well.UUCP>, ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab) writes: > > I have a MultiTech 224E error correcting modem. It's got automatic > fallback, both flavors of Hayes compatability, etc. It also has MNP error > correction in hardware. > > I've been having trouble with this. When I call up some local > non-MNP modems in Auto-Reliable mode (as the manual calls it), I get > garbage, as though the modem I'm calling is running at the wrong baud rate. > Sometimes (rarely), this doesn't happen, and I get a good connection (with a > non-MNP modem (by the way, I've never connected with an MNP modem)). > > Am I doing something wrong, or is the act of MNP handshaking causing > the destination modem to see a framing error, which many systems interpret > as a signal to change baud rates? Yes, the auto-reliable handshake isn't always transparent and will send garbage to non-MNP modems. The same thing happens with Microcom AX2400s so it's not just the Multitech that's doing it wrong (I have one of those too). What I do is simply not use it. I just set the modem to either MNP or non-MNP depending on who I'm calling (in fact my terminal program does this for me). I am also not crazy about it because it takes longer to connect to non-MNP sites since it first has to decide whether the other is MNP or not; this takes a few seconds. However, we do have our dialin Microcoms set to auto-reliable. This way both MNP and non-MNP work fine when they dialin (and no glitch seems to be transmitted to the host). -- Robert N. Berlinger Systems Analyst, Scientific Computing Center Compuserve: 73047,741 Albert Einstein College of Medicine Easylink: 62956067 UUCP: ...{philabs,cucard,pegasus,rocky2}!aecom!naftoli GEnie: R.Berlinger