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Reports until 18:10, Wednesday 16 December 2015
H1 CDS (CDS, GRD, Lockloss)
sheila.dwyer@LIGO.ORG - posted 18:10, Wednesday 16 December 2015 (24276)
Epics freeze SR3 cage servo lockloss

Dave, Sheila

At 00:47 UTC, we lost lock after a 45 second epics freeze.  The attached screenshot shows that the cage servo stopped updating, durring the freeze, which is the intended behavior since we modified the guardian (22754) to watch and not update the servo when the PITMON does not update. 

Dave looked up the guardian logs, and indeed the guardian does have the intended behavoir.  However, when the servo comes back on after being off this long it puts out a large number.  Now we have added a counter that gets incremented when the PITMON has not updated, and cleared when it is updated.  If PITMON has not updated in 16 cycles, the guardian will go to CAGE_SERVO_OFF, then should return to CAGE_SERVO_RUNNING and reinitalize the servo.  This will happen once a second until the epics freeze is over. 

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