[Hps-controls] HPS controls meeting, Tuesday October 15, 2013

[Hovanes Egiyan]

Hi all,

I posted the minutes of todays HPS slow controls meeting at:
https://confluence.slac.stanford.edu/display/hpsg/2013.10.15+Biweekly

Hovanes.


    Minutes

Present at JLab: Krister, Stepan, Nerses, Hovanes

Present at SLAC: Sho, Pelle


            SVT Interlock

Hovanes presented some ideas on implementing the SVT interlocks. The 
main point was that if we do not need an interlock system that shuts off 
the SVT power supplies and the SVT chiller, then we could use 
Allen-Bradley PLC for the interlocks since he thinks it will be 
relatively easy  and reliable system.

Pelle and Sho said that they discussed the issue of the interlock delay 
with other SVT experts and they did not see any problem with 100ms delay 
for the interlocks.

Stepan suggested to get estimates from a dealer to see what the savings 
are. Hovanes will try to get an estimate for a system with modules for 
the SVT interlocks only, and also for a configuration with some 
thermocouples (24 to be precise).

Krister asked if it was possible to use PLC for the HPS stepper motors 
as well. According to Hovanes, it is possible to use PLC for the motors, 
and many do it, but interfacing with EPICS will not be as simple, he was 
pretty sure the the existing EPICS support for EthernetIP does not 
include motor record which is the the record type that Hall B has always 
been using.  Stepan also thought it would be the best to keep the 
OMS-based system for the HPS since there is not enough time for 
developing and testing a new system for HPS when we have a working 
system from CLAS.

Krister and Pelle also suggested that a similar system can be 
custom-made using chassis with micro-controllers, so the question will 
again come down to the cost efficiency.


            ECAL scaler readout

The question was raised by Hovanes,  and was if the scalers from ECAL 
will be coming from the FADC250 modules or the JLab discriminators, in 
order to be able to prioritize the efforts for EPICS driver developments.

Stepan said that there has not been a final decision on whether to keep 
or drop the JLab discriminators from ECAL, but he thought that we would 
gain little by keeping them. Therefore, the  we decided to consider 
FADC250 scaler implementation in EPICS as a high priority item.


            Beamline

Krister have not had time to do much work on the beam-line controls last 
couple of weeks.

Stepan needs to have the pair spectrometer magnet controls to be 
connected to the magnet sometimes next spring when is moved donwstream.

Stepan also would like to connect the mini-torus power supply to the old 
pair-spectrometer magnet since the cables are already there. Also he 
would like to be able to ramp one of the Frascatti magnets to 1050A. 
Krister pointed out that he will need to check if the cable ratings are 
sufficient or he may need to use two sets of cables. This tests do not 
need EPICS and can use front panels of the power supply and the 
gaussmeter. The Frascati magnet tests are only for short-term, we will 
not need to go to 1050 Amps during HPS.

Krister mentioned that the Dynfysic rep was here at JLab recently, and 
he showed the Hall B pair spectrometer power supply to the rep to see if 
something can be done regarding the problem with the current bouncing 
around by hundreds of Amperes when the set-point was set to 0Amps. The 
answer was that it was  a common problem for these types of power 
supply, and it is possible to fix it by driving 5A or 10A internally. 
Noone from present people objected to this solution, provided we did not 
have to pay an arm and a leg for it.


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