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AT Command Set and S-Registers
Table 4-1. AT Command Reference (13 of 18)
AT
Command Description
&D n
Data Terminal Ready (DTR) Control
This command controls what actions are taken by the modem
based upon the Data Terminal Ready (DTR) signal.
&D0
&D1
&D2
&D3
NOTE: DTR has to remain off for a minimum amount of time
before the modem will perform any of the actions for this
command. This minimum time period is determined by the
setting of S-Register S25. If DTR is off for less than that time
period, no action is taken. See S25 for more information.
&F
Load Factory Defaults
This command loads the factory configuration options into the
Active Profile area and puts the modem in data mode.
&G n
Guard Tone
This command determines whether guard tones are sent out
while the modem is connected to a remote modem.
Guard tones are not used in North America but are mandatory
in some countries outside of North America.
&G0
&G1
&G2
Reserved. Should always be set to &J0.
&J
4-14
Issue 1 November 1994
The modem ignores DTR and assumes it is always
active.
The modem switches from data mode to command
mode when an on-to-off transition of DTR is detected.
(An ATO will return the modem to data mode.)
An off-to-on transition of DTR causes the modem
to go on-hook (hang-up) and disable auto-answer
mode. Auto-answer mode is enabled again when
DTR is turned back on.
An on-to-off transition of DTR re-initializes the modem
but does not perform a complete power reset.
Disables guard tone.
550 Hz guard tone enabled.
1800 Hz guard tone enabled.
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