Harlan Stenn wrote: >>>> In article <4944eab4$0$12693$9b622...@news.freenet.de>, Juergen Kosel >>>> <juergen.ko...@freenet.de> writes: > > Juergen> Hello, Greg Dowd schrieb: >>> I'm not quite sure what you mean. A reference clock doesn't compute an >>> offset, it acquires, formats and returns a time value from an external >>> source. NTP takes care of the rest. > > Juergen> ntpd reads the time of a reference clock with a reference clock > Juergen> driver. My problem was, that I didn't know from the manual what > Juergen> need to be done with the time from the reference clock. > Especially Juergen> when it is in a differnet format than of the other > reference Juergen> clocks. > > Juergen> But finally I succeeded by calculating the difference between > Juergen> refence clock time - system clock time and using the SAMPLE() > macro Juergen> to insert this value into the the right data structure > entry of Juergen> ntpd. > > > Juergen, > > Most refclock drives do not do it the way you describe. > > They take the time from the reflock along with the system timestamp (with > the intent to get the system timestamp as close as possible to the moment > the refclock timestamp is obtained), build the contents of the struct > refclockproc, and call refclock_process(). >
Hi Harlan, Hi Juergen, The difference is bit more subtle. 'refclock_process()' *will* call 'refclock_process_offset()', but *only* if the clock conversion in 'clocktime()' was successful. That means that the difference between local time and clock time is less than 4 hours! That's why initial synchronization with clocks only can/will fail if the system has no battery-backup clock. (That's probably true for most, not all clock drivers.) Calling refclock_process_offset()' directly will save that hassle, and it might provide initial synchronization even if the system clock is way off from the real time, for a given value of real 8-) -- juergen 'pearly' perlinger "It's hard to make new errors!" _______________________________________________ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
