Following on from the trouble locking the FSS that Corey, Keita and Jim had on Tuesday (alogs 55402 and 55427):

 

The FSS autolocker will remain in state 0 searching for a mode until  -0.3 < H1:PSL-FSS_PZT_RAMP_MODEPOS < 0.3. Recently we have been stuck here. This value is a measure of mode centering on the PZT range, found while the PZT is sweeping at 20Hz (for H1). 0 being in the center of the PZT ramp and +/-1 at the end. the autolocker should grab a mode, adjust the temperature to get the mode within the central 30% of it's range and then move on.

This works at Livingston (attached image), however at least since January (maybe the whole of O3), this has not been the case for us (attached image). It seems that the temperature change drags the modes the wrong way and we have just been lucky to grab a central mode. something must have changed this week to stop us being lucky and brought to light this problem.