LIGO Document E1400107-v2

ECR: store suspension mis/alignment values separately in EPICS database

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Document type:
E - Engineering documents
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Currently the suspension front end models create only a single set of EPICS records for setting pitch/yaw alignment offset values. However, there are multiple alignment states that need to be stored for each suspension. The current procedure therefore requires saving the offsets out-of-band, in separate files on disk. This introduces multiple problems, such as synchronization issues (stored offsets out of date) and additional management headaches (maintaining external scripts and files).

We propose adding additional EPICS records in the suspension front end models so that the aligned and misaligned state pitch and yaw values can each be stored separately. This would completely eliminate the need for a separate out-of-band process for managing the alignment settings by allowing us to utilize all of the existing infrastructure. The settings will automatically be stored in the safe.snap files, and in frames and conlog. We will always be able to restore to the most recent alignment settings without requiring additional work by the commissioners, and we will more easily be able to track alignment trends over time.

Files in Document:
Other Files:
ECR SUS alignment
Notes and Changes:
Includes updated version of planned implementation, calls out specific library parts affected, and includes updated time estimate.
see integration issue #746:
approved 3/14 by Dennis Coyne, Peter Fritschel, Valera Frolov, Brian O'Reilly,
(but without advice of the magnitude of the integer n; 5 seems sufficient to D. Coyne)
Referenced by:

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