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On Nov. 18, 2020 saw a failure mode where hsd_4 did not respond on configure phase 2.  Matt tracked this down to the fact that the kcu→hsd links weren't locked (visible with "kcuStatus" and "hsdpva").  Note that kcuStatus is currently not an installed binary: has to be run from the build area.  This was caused by the fact that we were only running one-half of a pair of hsd's, and the other half is responsible for setting the clock frequencies on the kcu, which is required for link-lock.  We set the clock frequencies by hand running "kcuStatus -I" (I for Initialize, I guess) on the drp node.  Matt is thinking about a more robust solution.

When we attempted to test the DAQ in SRCF with a couple of HSDs, we initially had trouble getting transitions through.  The two "sides" 1_DA:A and B behaved differently with pgpread.  Sometimes some events came through one side but not the other, but with significant delay from when the groupca Events tab Run box was checked and not when the transition buttons were clicked.  Also some of the entries in hsdpva's tabs were odd (Buffers:raw:freesz reset to 65535 for one, 4094 for the other).  Some work had been done on the PV gateway.  hsdioc on daq-tmo-hsd-01 had been restarted and got into a bad state.  Restarting it again cleared up the problem.

Cable Swaps

hsd cables can be plugged into the wrong place (e.g. "pairs" can be swapped).  They must match the mapping documentation Matt has placed at the bottom of hsd.cnf (which is reflected in the lines in hsd.cnf that start up processes, making sure those are consistent is a manual process).  Matt has the usual "remote link id" pattern that can be used to check this, by using "kcuStatus" on the KCU end and "hsdpva" on the other end. e.g.

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