Experimental Physics and
Industrial Control System

Peregrine McGehee <[email protected]> · Wed, 31 Oct 2001 20:44:27 -0700

We have an IOC configured as a soft timing slave with no
master IOC on the subnet so it is syncing with our NTP
server once every 10 seconds.

While the reported correction factors are always reasonable
- of order 0.0003 - and we see the difference between the
IOC and NTP time recover the 0.03 seconds lost every 5 minutes
when looks again for a master timer, we find that the IOC
will sometimes and suddenly fall behind in chunks of about
10 seconds - and never recover. The IOC has been as much
as 40 seconds behind the NTP clock.

Has anyone ever seen something like this before? Could it
be significant that the quantum of lost time is about the
same as the NTP sync rate? 

We are running EPICS R3.13.1 on MVME-162s (old style and 
Petra) and vxWorks 5.1.1.

Aloha,
	Peregrine
-- 
Peregrine M. McGehee		(505) 437-6822
Sloan Digital Sky Survey	Apache Point Observatory

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System