I revived the SUS_PI guardian to help with the PI damping issues we've been having with TCS tuning, code is in $(userapps)/sus/common/guardians/SUS_PI.py . This guardian is extremely simple and hard-coded so far, we can get more fancy as needed. See for example an attachment of what the guardian does that typically a human does: when mode {24,31} gets too big (according to its RMS MON), it scans the damping phase, while sitting with DAMPING_GAIN=1000.
If IFO loses lock, SUS_PI guardian will go down, i.e. 'IFO_DOWN' (PI ESD master output drive turns off, all gains turned off, PLL integrators cleared). SUS_PI can be found on the full GRD_OVERVIEW screen, and I've also (sloppily) put it on the PI screen for easier access as we setup. SUS_PI left in "PI_DAMPING" overnight, we will see how it does, please feel free to take it to "IFO_DOWN" if anyone likes.
SUS_PI has been loaded as a node into ISC_LOCK guardian, Austin reloaded the ISC_LOCK while we were in a lockloss and SUS_PI is now being managed by ISC_LOCK.
To start, I added the request nodes['SUS_PI'] = 'PI_DAMPING' at Line 5736, hidden in the "INJECT_SQUEEZING" state. SUS_PI will only turn on gains for PI_DAMPING if a monitored mode rings up, otherwise damping will be left off.
To damp PI's without the guardian, from "IFO_DOWN":
1) Request "PI_DAMPING", manual if you have to.
2) Go to "IDLE". This way the guardian won't fight you while scanning PLL phases.
In IFO_DOWN, guardian will turn off PLL integrators and the output drive to test masses. In PI_DAMPING's "main" state, it will initialize the PLL for modes 24, 31, and turn on the ESD drive to ETMY, so you want to go through PI_DAMPING to get started.
