[ntp:questions] Setting the COM port for the NMEA driver

Dave Hart davehart at gmail.com
Wed May 13 02:58:21 UTC 2009

On May 9, 3:24 pm, "David J Taylor" wrote:
> Folks, I made some tests with various settings for the NMEA driver and the
> results are here:
>  http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html#usb

Congratulations on showing serial PPS refclock connected via a USB
RS-232 adapter can do so well.  I did not expect you to match internet
performance, and you substantially exceeded the performance you were
getting with a refclock one LAN hop away.  I believe it is time to
update the conventional wisdom on connecting a refclock via a USB
RS-232 adapter.

> Maarten's guess about how to specify the COM port was correct (thanks),
> but setting a port above COM3 failed, so I have created bug report 1183.

Bug 1183 is resolved in 4.2.5p175, which removes the long-deprecated
"typeunit" array that meant unit numbers had to be less than 4.  In
theory ntpd on Windows should support COM1: through COM255:, and David
Taylor verified COM4: now works.

Dave Hart

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