[GTALUG] mysterious restarts

[Michael Galea]

On 06/22/16 21:44, James Knott via talk wrote:
> On 06/22/2016 07:39 PM, Michael Galea via talk wrote:
>> If I really needed to know the answer to the question of "how much
>> out", I would get ask the PLC to just count cycles and send me the
>> count with a timestamp. That would tell.
>
> And how accurate is the PLC?  Typical CPU clock crystals aren't that
> accurate.
>

There are a few answers here.
If you just run the device stand alone the data sheet 
(https://cdn.selinc.com//assets/Literature/Product%20Literature/Data%20Sheets/751A_DS_20150206.pdf?v=20150812-085325) 
promises "Unsynchronized Clock Drift Relay Powered: 2 minutes per year".

If you use IEEE1588, 1uS.
If you use NTP, well.. 1 mS?  That's the figure I always plan on.

-- 
Michael Galea