I don't remember us ever noticing BS M2 DAC glitches in ER7. The only ones we really saw were on MC2 M3. Looking back at two locks (Jun 5 5 UTC and Jun 8 14 UTC), BS M2 was centered on 0 with a peak-to-peak range of 6000 counts. So we don't really know what happens when we hit +/- 2^16 counts. I think we've seen that the -2^16 crossing is often the worst.

I just looked at some zero-crossings in MICH and the BS M2 noisemons during these two locks. Three quadrants look to be clear of DAC glitches. But in the UR noisemon there seem to be glitches at 300 Hz which match up pretty well with the times of zero crossings. The first attached plot is the Omega triggers of the noisemon with vertical lines showing zero-crossings in MASTER_OUT. The second plot is a different lock, where the conclusion still holds but the timing seems less exact. Next is a spectrum comparison of the UR NOISEMON versus MASTER_OUT. There's a notch around 300 Hz, presumably to avoid ringing up the BS violin modes, but the noisemon sees something coming out of the DAC in this range. For comparison, the other spectrum is the same thing for LR, where there doesn't seem to be excess noise in the notch.

I don't see any evidence of these glitches affecting MICH (I think that's where BS glitches would show up the best). That's probably why we never noticed these. We mostly look for things that affect DARM, although we sometimes serendipitously find other things (we noticed MC2 because it showed up in MCL). It's weird for DAC glitches to show up at high frequency, and the timing doesn't exactly match the zero crossings. It's probably worth keeping a close eye on the noisemons if more range is used on the DACs, and for detchar to check whether the DAC glitches had any effect on the BS stability.