[ntp:questions] Adjust serial device speed in ACTS refclock driver?
nomail at example.com
Mon Oct 6 06:57:42 UTC 2014
Rich Wales <richw at richw.org> wrote:
> Replying to Brian Inglis:
>> Modem cards would run at whatever interface rate the system set,
>> e.g. 19,200 or 115,200, and use the remote connect info to set the
>> line speed.
> I would normally expect a "sane" modem to act as you described. But
> this TrendNet TFM-561U appears to be tying the telco line speed to be
> the same as the system serial port speed.
>> The NIST ACTS supported range is 1,200-9,600. . . .
> I have tried connecting manually (via the "cu" command), and if I use
> any local serial port speed other than 1200 bps, I am completly unable
> to connect to the NIST ACTS -- the modem noise cycles through several
> different tones, apparently trying to negotiate a mutually acceptable
> speed, but eventually it times out and hangs up.
This depends on your modem and its settings.
Many modems can communicate with the system at 115.200 baud and still
use all their available line standards to do the real connect. Other
modems may use the communication speed as a hint about what line standard
they should attempt. E.g. when you communicate at 1200 baud, they will
try to connect using V.22 and when you use 19.200 baud they try V.32.
Check your modem manual, in the section with all those cryptic ATSxx=yy
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