aLIGO LHO Logbook

H1 IOO

paul.fulda@LIGO.ORG - posted 20:22, Wednesday 06 February 2013 - last comment - 15:56, Saturday 09 February 2013(5399)

IMC locking - length path lock filter limit reset to 400,000 counts

[Hugo, Rodica, Paul]

Today we were finding it impossible to lock the IMC again. When we looked at the SUS-MC2-M3_LOCK_L_OUT_DQ channel, the signal appeared to be always railing (on both sides). We have seen this before at times, due to very noisy seismic states (see e.g. entry 5145). However, even with what we expected to be a quiet siesmic and ISI state, we still found this signal railing at ±40,000 counts, making it impossible to lock using the length path. In the end, Hugo realised that when the model was recently updated, the limit on the MC2 M3 lock filters had reverted to its initial old value of 40k counts. Apparently at some point this was increased to 400k counts, but not saved in a safe.snap file. Hugo increased the limit back to this value and the mode cleaner began locking again.

We should update the safe.snap file so that any further reboots revert to the 400k counts limit.

Comments related to this report

jeffrey.kissel@LIGO.ORG - 07:53, Thursday 07 February 2013 (5402)

Link

You can make a new safe back up easily, by turning off all output (damping loops off, offset off, and master switch off), then running
/opt/rtcds/userapps/release/cds/common/scripts/makeSafeBackup
The usage is

controls@opsws2:~ 0$ cd /opt/rtcds/userapps/release/cds/common/scripts
controls@opsws2:scripts 0$
controls@opsws2:scripts 0$ ./makeSafeBackup
Usage:  First argument is subsystem name (i.e. sus, isi, hpi, isc, etc)
Second argument is model name (without .mdl) (i.e. l1suspr3)
controls@opsws2:scripts 0$ ./makeSafeBackup sus h1susmc2
controls@opsws2:scripts 0$

this updates the safe backup here,
/opt/rtcds/userapps/release/sus/h1/burtfiles/h1susmc2_safe.snap
which you should then commit to the SVN with appropriate comments on what has changed.


Also, I believe Mark has a matlab function that sets up the suspension in the right setting for the safe capture, and does the capture, if you prefer that.

paul.fulda@LIGO.ORG - 15:56, Saturday 09 February 2013 (5443)

Link

Thanks Jeff, I have now done that (I hope succesfullly). I left all the gains, limits, etc. in the useful condition for locking, but turned off all the damping filters, lock filters, alignment offsets and master switch, and then committed the new safe.snap files to the svn.