Recently it has become apparent that veto logic through all the PLC systems needs to be reviewed. I think the initial documentation for the PMPS did not really focus on veto logic and so it wasn't consistently implemented. Additionally, many of the veto devices have only recently been added.
Bill Schlotter reported that during some beamtime on the K line the undulators were set to an unusually high K value. This put them out of our current setting for active range (PMPS Photon Energy) so no seed undulator could be found, resulting in a calculation for eV of 0. The actual effective eV was around 600eV. The photon energy bitmask was then set to 2#0000_0000_0000_0001 which was inaccurate and problematic as it circumvented some faults. To fix this issue I changed the bitmask logic so a value of zero will result in the current photon energy bitmask being set to 2#1111_1111_1111_1111.
We have been planning for a while to have the RIXS optics PLC send its mono grating pitch values directly to the LCLS2 DAQ. This was deployed this PAMM, through a joint effort between Zachary L Lentz, Christopher Ford, Margaret Ghaly, and Jyoti, Joshi. The encoder can be selected in the DAQ, at which point it will send triggers directly to the PLC, which responds appropriately up to 60Hz. The plan was to respond appropriately up to 120Hz, but this issue was not caught until nearly the end of the PAMM. There will be follow-up work to get this to work properly at 120Hz.