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That's a check to make sure that the LCLS1 fiducials are arriving on boundaries of 71kHz (any multiple of 1666 - 119 MHz clocks).

LCLS2

Upstream Timing Issues

This does not apply to LCLS1 timing, I believe.

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One of these "outs" goes to a local fanout in 208, which then drives xpm0.

Triggers/Transitions Behaving Erratically

Saw this after an ACR timing system outage on May 22, 2024.

Transitions weren't transmitted from xpm3.  Fixed-rate L1Accepts seemed to go in bursts.  Dumped out xpm3 frames to log file with xpmpva.  Saw that the readout group messages were stuck.  Fixed with a TxLinkReset to xpm3 (from xpm0).  May have also been fixed with an RxLinkReset in the xpmpva UsTiming tab of xpm3.

Trigger Delays

See also Matt's timing diagram on this page: Bypass Events

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