In today's HAM6 vent meeting people asked if the shutter was working at all. It still works.

The first attachment shows that the shutter closed (green trace) last night when the IFO lost lock. Brown is the tirigger voltage, and the trigger threshold is 2V.

Red is the OMC DCPD, blue is the DC of ASAIR_A, vertical lines indicate where the shutter triggered.

Due to some strange timing problem of Ethercat signals transported to EPICS that was reported in alog 17445, you cannot compare the timing of the green and the brown trace with red and blue, so the trigger timing on this plot is just a guesstimate obtained as follows:

1. Trigger voltage (brown) is produced in ASC AS_C interface box by adding all four segments in analog, and the analog output is directly plugged into the shutter box. This voltage is just AS power, so is supposed to be proportional to ASAIR_A_LF (blue).
2. Before the IFO lost lock, trigger voltage was 0.12Volts, ASAIR_A_LF was about 1200 counts, so the equivalent trigger threshold for ASAIR_A_LF would be 20000 counts where the shutter should have triggered.

The second plot shows that the shutter has been firing all the time for recent 100 days.

One thing that is strange is that the LSC-ASAIR_C_LF_OUT_DQ is recorded on the frame at 16kHz but the input is grounded in the frontend. If my memory is correct Dan Hoak wanted to record the trigger voltage at 16kHz, and my guess is that ASAIR_C_LF was supposed to be used for this because it's not used, but nobody implemented it.