Data Terminal Ready: Difference between revisions

Revision as of 13:13, 25 March 2010

Revision as of 21:06, 29 July 2011

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===DTR configurability on modems===

{{Mergeto| Modem| discuss=Wikipedia:Articles for deletion/Data Terminal Ready |date=November 2009}}

Virtually all modems new enough to support error correction and data compression (all modems 9600 bps and above, and some 2400 bps ones as well) have a built-in capability of modifying what they do with RS-232 signals, depending on the application.{{Citation needed|date=November 2009}} 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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* [[Ring Indicator]]

[[Category: RS-232 signals]]