This morning we tested and put on line an AlpInj macro, "adjust_EIBrotator", that takes care of monitoring the TraMC power and of compensating for drifts and slow fluctuations by rotating the motorized waveplate on the EIB.
The set point is obtained from the BC DSP (Gname=PwrDc_set) and
the error signal is computed from the IMC transmitted power (Sc_IB_TraMC ).
The loop is part of AlpInj default macro and it is normally active. The correction signal (in degrees) is clipped in case it is too large, and sent to the Rotator server after haviing performed and passed a few checks:
- IMC locked,
- MC AA and IB AA loops ON and properly working
- good PMC output power
- rotator position in a pre-defined working range
- correction higher than a minimum quantity

The rotator steps might cause glitches on the ITF. To be verified.
The servoloop tuning is not optimized and could be needed a further tuning after the analisys of long term performance.

In case of problems, disable the loop by launching the "Set_EIBrotator_servoloop" macro from AlpInj .