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Pointillist (talk | contribs) →DTR configurability on modems: clarify which commands are standard, add five references |
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===DTR configurability on modems===
Virtually all newer{{when}} modems have a built-in capability of modifying what they do with RS-232 signals, depending on the application. The [[AT command]] for manipulating DTR is typically <code>AT&D</code> followed by a single digit.<ref>{{Citation |title=The Extended Hayes Command Set | publisher=[[KDE]] |url=http://docs.kde.org/stable/en/kdenetwork/kppp/hayes-extended-commands.html |accessdate=2009-11-23 }}</ref> AT&D0 and AT&D2 are mandatory under V.250, and AT&D1 is optional.<ref name="V250_6_2_9" >{{Citation |title=V.250 : Serial asynchronous automatic dialling and control (05/99, 07/03) |chapter=6.2.9 Circuit 108 (data terminal ready) behaviour |publisher=[[ITU-T]]/Telecommunication Standardization Bureau |url=http://www.itu.int/rec/T-REC-V.250/en |format=PDF}}</ref> AT&D3 is non-standard but widely implemented,<ref name="USR_Courier_Ch8">{{Citation |title=Courier V-Everything Command Reference |publisher=[[U.S. Robotics]] |url=http://www.usr.com/support/3453b/3453b-crg/chap%208-controlling%20EIA-232.htm |chapter=8. Controlling EIA-232 Signaling |accessdate=2009-11-23 }}</ref><ref name="MS_PnP_1995" >{{Citation |title=PnP for COM Devices, rev 0.92 |format=RTF |publisher=[[Microsoft]] and [[Hayes]] |url=http://download.microsoft.com/download/1/6/1/161ba512-40e2-4cc9-843a-923143f3456c/pnpcom.rtf |date=February 28, 1995 |chapter=A.4 AT&D3 Implementation Issues }}</ref> and higher values are used by some vendors.<ref >{{Citation |title=Alpha Micro GPRS Modem Functional Overview 1.0|url=http://www.alphamicro.net/resources/GPRS_functional_overview.pdf |accessdate=2009-11-23 |year=2003 |author=Nick Robins |publisher=Alpha Micro Components |format=PDF}}</ref>
* '''AT&D''' or '''AT&D0''' - Ignore DTR signal. A call will continue regardless of the DTR line, and the only way to end the call is with the escape sequence, or if it gets terminated by the other side. This setting is only used if the computer equipment cannot provide or control DTR.
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