[Halld-controls] PXI Time Stamps

[Beni Zihlmann]

I think yes we should do this.

On 09/04/2018 09:36 AM, Timothy Whitlatch wrote:
> Hi Brian,
>
> We will have time this week to reboot the PXI (Just not today).
>
> Hovanes and Beni, do you think we should implement the fix this week?
>
>
> Tim Whitlatch
> Hall D Engineer
> Jefferson Lab
> 600 KELVIN DR STE 5
> Newport News, VA 23606-4468
> 757-269-5087
>
> ------------------------------------------------------------------------
> *From: *"Brian Eng" <beng at jlab.org>
> *To: *"Hall D Controls" <halld-controls at jlab.org>
> *Sent: *Thursday, August 30, 2018 1:46:47 PM
> *Subject: *[Halld-controls] PXI Time Stamps
>
> We recently discovered that the time used by the PLCs has a offset to 
> it which causes them to use/provide an incorrect time.
>
> It manifests itself in 2 ways:
> 1) If the CC server is the master the PLC will be 34 seconds fast
> 2) if the PLC is the master any devices on the same subnet will be 34 
> seconds fast
>
> That 34 seconds is hard-coded in the PLC ethernet module and only 
> changed by upgrading the firmware (but it still won't be user 
> adjustable). It comes from the offset between UTC & TAI time when the 
> module was purchased.
>
> Currently we're operating in the second configuration.
>
> There is an option to correct this offset with Linux based NI devices, 
> but I haven't yet tested it with the other OSes (namely the PXI which 
> uses Phar Lap).
>
> Unfortunately even if I can remove this offset it will require 
> rebooting the PXI, so my question is should I try pursuing fixing this 
> or is knowing that there is a fixed & constant offset good enough for now?
>
>
>
>
> P.S. This isn't like the earlier time problems we had where the time 
> would slowly wander off, this is a fixed value with only the error of 
> PTP coming into play which should be at the sub-ms level.
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