Experimental Physics and
Industrial Control System

Ralph Lange <[email protected]> · Fri, 03 Jul 2015 11:33:16 +0200

Hi Yuliang,

The NTP sync interval is a compile time constant, thus it cannot be

changed at run time.

One question, though.

Your time report shows that the measured tick rate is 60.007 Hz, which

is a difference of about 2 us per tick, 120 us per second, 7.2 ms per

minute. Time resolution is in ticks, i.e. 16.67 ms. That means the NTP

sync will skip a single tick in the counter every two or three minutes.

Why do you want to change the sync interval?

Setting it longer will make the situation worse: more than one tick will

be skipped at larger intervals.

Setting it shorter will increase network traffic without changing the

situation much: a deviation of 7.2 ms per minute will always be

corrected by skipping one tick after between two and three minutes.

Cheers,
~Ralph

On 03/07/2015 10:36, Zhang Yuliang wrote:

Hi all,

I want to know how to set the NTP time sync interval on vxWorks. The output of "NTPTime_Report 1" shows the default interval is 60 seconds:

timingMain>NTPTime_Report 1
NTP driver is synchronized with server
Syncronization interval = 60.0 seconds
Last synchronized at 2015-07-03 16:06:19.062927
OS tick rate = 60 Hz (nominal)
Measured tick rate = 60.007 Hz
NTP Server = 10.1.201.31
value = 0 = 0x0

I can modify the variable "NTPTimeSyncInterval" in file $(EPICS_BASE)\src\libCom\osi\osiNTPTime.c to change the sync interval. Is there a command can be used in ioc shell?

Best regards,
Zhang Yuliang

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System