Date: Mon, 29 Jan 96 21:23 WET From: uhclem@nemesis.lonestar.org (Frank Durda IV) To: freebsd-hackers@freebsd.org Subject: Re: Multi-Port Async Cards Message-ID: <m0th6fi-000COnC@nemesis.lonestar.org>
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[1]Yes, it will reset itself, but even if you keep DTR down, it will answer [1]the phone after it has reset itself. I don't know for sure about supras, [1]but most brands sold here work like this. [3]There are only 4 modems I know of that do this, and all but one of them is [3]no longer manufactured (and two of them were from Radio Shack and could [3]not handle binary transfers anyway). FYI, the function of &D2 (yes D-TWO) is defined in the ANSI/TIA/EIA-602-1992 specification, and it clearly states that: (section 6.3.9 Circuit 108 DTR Behavior) &D2 Upon an on-to-off transition on circuit 108/2 (DTR), the ACE instructs the DCE to perform an orderly cleardown of the call. Any data in the DCE pending transmission to the remote DCE is sent before the call is cleared, unless the remote DCE clears the call first (in which case pending data is discarded). The ACE disconnects the DCE from the line. Automatic answer is disabled while the 108/2 (DTR) remains off. **************************** ********************************* The Hayes definition of &D3 (plus everybody who copied Hayes) is to do everything &D2 says to do, PLUS reset the modem registers to the settings stored in non-volatile RAM if present, or if there are no stored settings, to restore the factory settings. Once the settings are restored, the modem returns to Command Mode. Some modem vendors achieve the above by re-executing the power-up-reset code in the modem controller. How it is done is up to the individual modem maker because the &D3 command is not part of ANSI/TIA/EIA-602 specification. I know I haven't come across a V.42bis modem (2400 and up) that has not implemented &D2 and &D3 as stated above, which includes disregarding incoming calls when DTR is deasserted. I can state that Telebit 2500, 3000, WorldBlazer, Sierra-based modems, Couriers (back as far as the HST days) and modems from many other vendors (even some cheap Packard Bell EasyData 2400s I used to own) all ignore incoming calls in &D2 or &D3 when DTR is deasserted. If your modems don't have &D3 for some reason, simply store &D2 in the modem and have getty and outbound dialing scripts issue a ATZ before doing anything else when they re-open the line. This will provide the equivalent overall function of &D3. (Be sure you wait for an "OK" from the ATZ command before proceeding - see EIA-602 6.1.7 as there is no time limit on how much time ATZ takes to complete.) Frank Durda IV <uhclem@nemesis.lonestar.org>|"The Knights who say "LETNi" or uhclem%nemesis@rwsystr.nkn.net | demand... A SEGMENT REGISTER!" ^------(this is the fastest route)|"A what?" or ...letni!rwsys!nemesis!uhclem |"LETNi! LETNi! LETNi!" - 1983
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