Josh, Laura, Andy, Duncan, TJ,

Laura noticed that on 10/23/15 LSC X COMM CTRL was hitting its software limit (10 um) while H1 was locked, according to the nice software limits page set up by Duncan M on the summary pages. We've previously seen common mode tidal control hit software limits back on (17654 and 18748 and I remember but can't find the commissioning work to improve this). The attached plots show 1) the times when the software limits were hit, both near to the end of lock, but in lock (likely leading to lockloss), 2) the 24-hour min/max plot for the control channel, 3-6) the control signal and GDS CALIB STRAIN for the two saturation times (four saturation segments, two at each time). It looks like sometimes lock is acquired with the common-mode control being already quite close to its limits. This happens rarely, this is the only day in the past week we have seen it.