Re: [Bacnet4linux-developer] BACNet4Linux TimeSync

[Steve K. <st...@ka...>]

Hi Coleman,

> Isn't it true that if a device performs a time sync request then it's
> considered a time master?  

TimeMaster was one of the functional profiles.  If you claimed Time 
Master functional group, then you had to implement the list.  I think it 
was deprecated in favor of BIBBs in Addendum D to the 135-1995 standard, 
and now there is TimeSync and UTCTimeSync BIBBs.

In the 2004 version of the standard, Time Master is mentioned only 3 
times and each alongside time-synchronization-recipients, but there is 
no definition or reference in the PICS to the Time Master, so this is 
most likely a holdout from the 1995 standard that has yet to be fixed in 
todays standard.

Perhaps we should discuss it at the BTL or the next SSPC meeting, or put 
forth a proposal to eliminate the wording, or simply ask the SSPC for a 
clarification: what is a Time Master or what is definition of a time 
master? (but clarifications requests need to be answerable as YES or NO, 
so someone needs to do the research).

> Yes, that's precisely what my design called for.  The user tells my
> widget to get it's time from external time source (assuming an Internet
> connection), and my widget syncs its time with that source.  Then every
> 15 minutes (is this too often or not often enough? -- maybe
> configurable) my widget performs a time sync for everyone in its
> time-sync-recipient list (I'm implementing the BACnetAddress flavor).  

Configurable cycle time is preferable, IMHO.

Best Regards,

Steve
-- 
http://kargs.net/