Keita, Elenna, Ryan,
Keita noticed that the JAC was sometimes finding a resonance at a very low voltage offset on the PZT actuator and running out of range when it tried to lock near as it was near the bottom rail of the PZT voltage. See the photo for an example, the scan just keeps rampign from 0, finding a resonance but not lockign successfully.
They changed this from 0V to 50V to avoid this problem. This is channel H1:JAC-PZT_DRIVER_SCAN_START for reference and is set by the guardian to the correct value of 50V in the 'SCANNING' state.
Daniel also changed the H1:JAC-TRANS_A_DC_NOMINAL value from 0 to 0.0042. This was to give us a normalised cureent of around 1 on the JAC-TRANS_A beckhoff screen. This means that our trigger on level of 0.5 allows us to only trigger on larger fringes and not all the higher order modes.
This value looks like it was 0 before the power outage but was non-zero in March/April when we were commissioning. I think we must have missed this when we set the scan parameters in the guardian after initial commissioning in May 2026 and if the JAC is well aligned enough this is not so much of a problem as the HO modes are very small.
I also removed the checker form the PSL decorator state in the JAC guardian that checks whether the FSS is unlocked and if so sends the JAC guardian to fault. Keita/Ryan hypothesised this was causing the JAC to unlock every time the FSS did.
Once I commented this out Keita observed that this FSS unlock is happening when the 'BOOST' filter is engaged in the common mode board by the IMC guardian. I will recheck this offline.
Accepted JAC sdfs, the rets should be set by the guadrian.
