cheryl.vorvick@LIGO.ORG - posted 18:18, Tuesday 28 July 2015 - last comment - 11:07, Wednesday 29 July 2015(20009)
Breaking the IFO Lock for Maintenance:
For Maintenance this morning I needed to break the IFO lock, so recorded the steps used today.
- ISC_LOCK - setting ISC_LOCK to DOWN did not break the IFO lock
- requested IMC_LOCK to OFFLINE, but while IMC_LOCK is managed by ISC_LOCK, ISC_LOCK continues to relock the IMC
- setting ISC_LOCK to PAUSE allowed the change of IMC_LOCK to OFFLINE
- IMC_LOCK in EXC was still trying to put MC2 to MISALIGNED, instead of the requested state of SAFE, so was feeding signals to MC2 until IMC_LOCK was set to PAUSE
- Besty, Jeff, TJ, Cheryl
The reason that requesting ISC_LOCK to down doesn't work anyore is because I made down not a goto state. This means that there is no path from NOMINAL LOW NOISE to DOWN. (We were having problems with unintentially going to DOWN.) So when you request DOWN, the guardian doesn't actually go there. To force it to do that, you can go to manual mode and select DOWN.
I understand more now, and was not aware that you had changed that on purpose.
No suggestion for a change, just reporting what I was asked to try and the results I got.