Most modems support automatic reset upon loss of DTR signal (i.e.,
when your program closes the port at /dev/xxxx). This is performed by
AT commands. You need to save your configuration to the modem's non-
volatile memory in order for this to be useful. Something like this:
(to be performed only once per modem):
AT&D2
AT&W
This is what I recommend over any software methods, because it resets
the modem under *any* circumstances. However, this will only work
with lines providing DTR (i.e., COM2 will not work!); on the other
hand, you can emulate the DTR signal with an I/O port to accomplish
the same result.
Guille
--- In Jim Jackson <> wrote:
>
>
>
>
> On Wed, 23 Aug 2006, smithson_bonnie wrote:
>
> > Hi all,
> > I use ts7250 for dial out. After dialing out the connection is
> > established and CD on the US Robotic turned on (CD is Carrier
Detect
> > and this signal indicates if a dial tone is present. This will be
> > true when the modem is off hook and a dial tone is presents)
> >
> > If I kill the pppd process then pppd gracefully exits and CD on
> > modem will turn off. (I believe because pppd send +++AT command to
> > the modem and tells it to hang up the telephone line).
> >
> > If I turn off the TS7250 in the middle of dial out and pppd cannot
> > graceful exits, then the modem stuck and I cannot dial out again
> > after the ts7250 reset. The connect script will fail. In the log
> > there is a message "cannot turn off soft carrier". Basically I
> > cannot send any AT command to the modem anymore. I even use mgetty
> > and mgetty.conf to set ATZ command to the modem, but it does not
> > work.
>
> you need to set the serial line to ignore modem control lines
> use stty, and use the clocal option - see man page for stty.
>
>
>
> > Our ts7250 is connecting to another system and that system
controls
> > the power supply to ts7250. The system can do power cycle anytime
> > and it can happen in the middle of dial out (so pppd cannot
> > gracefully exits). Unfortunately the modem and the system are not
in
> > the same power source and nobody is physically there to turn off
the
> > modem.
> >
> > I want to add a script on the startup of ts7250 to turn off CD on
> > modem, but I do not know how. Someone had the same problem in Sun
> > Solaris and their suggestion is using the hardware carrier
detect,
> > /usr/etc/ttysoftcar -n /dev/ttyd0
> > and reconfig the kernel change the zs0 flag to 2,1 or 0
> >
> > But we do not have ttysoftcar in our TS7250?
> >
> > Please help!
> >
> > Thank you so much for your time
> > Bonnie
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
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