Josh, Andy, TJ, Duncan, Detchar, 

In 17791, Dan followed up the observation that COMM control was saturating by doing the most awesome thing - writing a script to identify all times when software limits are reached, by searching for all enabled software limits and then scanning data from those channels to see if 99% of the limit value was exceeded in a given time range. 

I asked Duncan Macleod if he could optimize this code and he did. Dmac said: I have a working version that uses multiprocessing and is significantly faster than the original, and I’m pretty sure returns the same result. I have also added functionality to record the segments during which a given channel was saturating its software limit, and write them all to a LIGO_LW XML file.

To test this code, Duncan ran it over the long locked stretch from roughly 9-23 UTC on 5/17/15 (range plot shown in attachment 1). The output XML is attached below. 

The primary limit saturations found were, a bunch near the end of the lock (probably after lock loss) and two in the midde of the lock: 1115927164.94, from H1:SUS-ITMX_L2_OLDAMP_P and 1115927158.19 from H1:PSL-ISS_DIGITAL_LOOP. Attachment 3 shows a normalized spectrogram of DARM during the saturation, 4 shows the timeseries of DARM, 5 shows timeseries for H1:PSL-ISS_DIGITAL_LOOP, 6 shows timeseries for the PSL PDB diode first loop intensity stabilization diode, 7 shows a saturation in H1:SUS-ITMX_L2_OLDAMP_P  at nearly the same time (which is real, but doesn't have a big noticeable effect in DARM), 8 is a saturation counter from the PSL that finds this time equally well.  

We plan to run this script for each lock stretch from now on to produce DQ segments and identify times when channels are hitting their software limits.