Re: EPICS Time provider, MRF TImestamp

["Johnson, Andrew N. via Tech-talk" <tech-talk at aps.anl.gov>]

Hi Alexis,

On Oct 12, 2021, at 9:37 AM, GAGET Alexis via Tech-talk <tech-talk at aps.anl.gov> wrote:

I have a MRF Timing system that is working well. I’m using Timestamp from the EPICS driver mrfioc2. I can see in my MRF IOCs that the Time provider is the “EVR”, and then all my PVs in those MRF IOCS are well timestamped.

But obviously in my other IOC (soft IOC or any other device IOC), I haven’t MRF Time provider and they are using the “OS Clock” as a timestamp reference.  I’d like to use the MRF Timestamp as reference for any IOCs in my system. Is there a way to do that ? declaring a new time provider from a PV ? I’ve tried to test to declare a new time provider without any success until then, if you have example it’s welcome.

The MRF time provider can only work when the system has an MRF receiver connected to a source of time events. Older versions of EPICS had an alternative way to synchronize time-stamps over the network for IOCs running on VxWorks, but it was quite crude and gave worse results than the sophisticated methods used by time sync daemons on Linux.

Sure my OS can be synchronized by NTP, but I have bad experience with NTP and I’d like to know if there is an EPICS way to do that.

The APS has switched our Linux systems from using ntpd to a newer daemon called Chrony which we find works much better, especially on systems that are running as a VM and not on bare metal. I believe there are now other choices as well, and you might also be able to use PTP instead of NTP for the network protocol, although we found that Chrony gave very similar results to using PTP.

HTH,

- Andrew

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