Sheila, TJ
After requesting a power for TCSX from the rotation stage medm, Sheila noticed that the RS was just spinning and not going to the correct power. She promptly hit abort where it stopped at 2W going into the IFO. Requesting a new power did not seem to work, nor did clicking abort one or five more times. This happened last week as well, but last time it mysteriously fixed itself. We weren't so lucky this time. We logged onto h1ecatx1 and pulled open some Beckhoff manuals and tried reading through the errors to diagnose why the RS got stuck. After about an hour or so of digging through errors, we traced it down the RotationstageIn.Warning flag coming from the hardware that may be stuck somehow, so we decided to force the warning to be False in the system manager and then all we well (after remembering to turn the autoabort back on). RS seemed to go to requested powers again without complaint.
When Sheila went to investigate the initial incident, she found that the RS had actually starting moving before a request right before this. She'll give more info on that later.
I was adjusting the differential TCS power in 100 mW steps and seeing no impact on the interferometer, and as a final step deicded to try 0 Watts of ITMX power and 0.2 Watts of ITMY power. This had a much more dramatic impact that the previous few similarly sized steps had, and caused the sideband powers to drop. I reset the request for ITMY CO2 to 0.1 (the previous setting) and reset it, then looke at X which was moving around to about 5 Watts. The attached screenshot shows when I set the request to 0 for ITMX CO2, and then the encoder and power meter readback start moving before the request is changed. When the interferometer looses lock the down state sets the request to 0,5 Watts for pre heating, but the rotation stage continues zooming up to almost 5 Watts of input power.
For FRSes, this cost us 2 hours so far, but it will probably take another hour or so for the test mass to cool off enough that our ASC works.