8 IP Modem Function
8.5.15 AT &F (factory settings) [AT&F0]
This command has historically been designed as "Reset to Factory settings", while ATZ simply
meant reset. At time of invention users could change the default behavior of their Modem, so ATZ
activated the stored profile.
Nowadays the ATZ is ignored by many software. Instead AT&F is used, followed by complex
initialization strings. User may save profiles, which are selected by AT&F0 or AT&F1. There is no
longer a documented or commonplace way to revert to Factory Defaults.
The IP Modem has such an option (clear the InitString via Telnet/web), but this is not usable
to reset the configuration when the device is used as a Modem. So IP Modem will support only
user profile 0, and it uses AT&F9 to really reset the user profile to the Factory defaults.
8.5.16 AT &C (DCD configuration) [AT&C1]
Configure the DCD signal to the PC. As IP Modem this signal may be generated by the DTR
output. A standard modem can have DCD always on, and it can have the DCD follow the external
carrier signal. When set to always on by AT&C0 the DCD may have a separate source. The DTR
is free to serve as a DSR to the PC. The operation of DSR is defined by AT&S, so these commands
are related. AT&C1 is the default, the DTR operates as DCD to the PC (this will require a cable
connecting NetCom
+
-DTR to the DCD of the PC).
This command has priority over AT&S.
8.5.17 AT &S (DSR configuration) [AT&S0]
Configure the DSR signal to the PC. As IP Modem this signal may be generated by the DTR
output. A standard modem can have DSR always on, as long as the Modem has power. Or it
can have the DSR signaling whether the IP Modem is in command or in data mode. When set to
always on by AT&S0 (this is the default) the DSR may have a separate source. The DTR is free
to serve as a DCD to the PC. The operation of DCD is defined by AT&C, so these commands are
related. An AT&S1 has DSR follow the data mode.
The AT&C has priority over this command. AT&S1 can only be effective, if AT&C0 is set.
8.5.18 AT &D (DTR configuration) [AT&D2]
Understand the DTR signal of the PC. The input on the IP Modem is the DSR, which requires
a proper serial cable. Usually this signal is either ignored, or serves to disconnect from the phone
line. There are four options:
AT&D0
Ignore DTR from PC
AT&D1
Toggle DTR to enter command mode
AT&D2
Toggle DTR to disconnect and enter command mode
default
AT&D3
Toggle DTR to reset the IP Modem
perform ATZ
Table 27: IP Modem DTR Configuration
September 2016
NetCom Plus User Manual
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