As part of the investigation into the cause of the laser trips, I looked at the
status of a few bits of the TwinSafe codes.  This is a rough core dump of my notes
from the session.

    The status screen was red on "Interlock OK".  The following values were recorded
bAmpNPRORunning = 0
bAmpShutterOpen = 1
bAmpShutterClosed = 0
bILOK = 0
bILTwinSafeFBError = 0
bILSoftwareEvent = 1

StandardQX1[0-7] = 11111111
StandardQX2[0-7] = 11100000, this indicates bILDChilFlow, bILXChilFlow and bILDiodeRoomSafetyKeyLock
                             are 1
StandardQX3[0-7] = 00000000
Standard1X1[0-7] = 00100000, this indicates that bILSoftwareEvent is 1 consistent with the
                             above observation
Standard1X2[0-7] = 00000000
Standard1X3[0-7] = 00000000

Seemingly the above suggests that at some point there was a problem with the chiller.
No indication on the chiller of a problem, in fact both chillers were still running.

    TwinCAT indicates that 1 frame (out of many tens of thousands) was lost.  I don't
know if this is enough of a loss to trigger the TwinSafe safety relay or not.