[Jenne, Stefan, Peter, TJ]

We now have a new guardian node, FAST_SHUTTER, to monitor the function of the fast shutter.  So far this does not interact with the PZT shutter. 

Attached is the guardian graph of how it works for now. 

• Down is currently an empty state.  The only thing I can think to perhaps add here is re-requesting that the shutter be closed. 
• CheckReady is the big state that does most of the work.
  • If the Beckhoff logic says that we need to run the tests (either it's been more than 48 hours, or something is wrong), then execute the test script that's also accessible from the new medm screen.
  • If we don't "need" tests, then check several of the ready bits and error flags to make sure they're all clear.  Also check that we have some non-zero amount of light on the trigger photodiode (threshold currently set to 0.25, typical value during 2W DRMI lock is 0.3 or so).
  • If everything is fine, go to the Ready state
• Ready is an empty state like that of ISC_LOCK, to help make it clear that you've successfully completed the Check state.
• TestShutter executes the Beckhoff test script.  If the shutter passes the tests, the script should clear the TestNeeded EPICS bit, so that when TestShutter returns to the CheckReady state, it'll go through with the rest of the checks, and hopefully return Ready.  If the shutter fails the test, the guardian instead returns ShutterFailure.
• ShutterFailure should be impossible to get out of without human intervention.  It's an empty state, but it'll keep things stuck until someone checks on things.
• IFO_Locked is currently empty, but should be made to watch for locklosses.  This is the nominal state for Observing.
• Lockloss should run some small analysis to ensure that the shutter did successfully close.  If it did not close, this should return to the ShutterFailure state, and keep us stuck there until a human checks things out.  Otherwise, it'll return Down and be ready for the next acquisition sequence.

So far, this is not incorporated into the main ISC_LOCK guardian.  However, ISC_LOCK Down should probably request Fast_Shutter's Down.  Somewhere around DRMI_LOCKED we should have the ISC_Lock guardian request Ready from the FastShutter guardain.  We shouldn't be able to continue locking unless the FastShutter says that it's Ready.  Somewhere like DC Readout, we should put the FastShutter guardian in IFO_Locked.

We hope to be able to test the functionality of this new guardian tomorrow, after ISCT6 is put back in place.