The laser tripped out again.  Attached are two plots of the flow rate signals around the time of the trip.
Bear in mind that the minimum head flow rate was set to 0.5 lpm.  The flow rate for head 4 had a small
excursion close to 0.5 lpm.  Zooming in on the low point shows the flow rate to be above this limit.
It might be that the flow rate may have dipped below this level faster than the sampling time between
TwinCAT/OPC and EPICS.

    Assuming that the flow rate in head 4 did not trip the laser out, then the problem lies with the
crystal chiller.  Not sure why at this stage.  One thing to try the next time is to swap where the
chiller(s) get their 3-phase power, ie interchange where the crystal chiller plugs in to where the
diode chiller plugs in and vice versa.  The chiller is relatively new, so it's hard to believe that there's
something wrong with it but at this point everything points in that direction - in my opinion.

    Most of the laser trips have been associated with the crystal chiller.  Even with the previous two
chillers that were used.  The only thing we did not change was where the crystal chiller was plugged in.
Swapping its power socket with the diode chiller might fix the problem or switch the problem over to the
diode chiller.

    The "electronic" flow sensors have been removed and the flow rate values have been forced within
TwinCAT.

    Should the laser trip out again, please do not bring it back.