Subject:
DIRC HV and alarms
From:
Christophe Thiebaux <thiebaux@poly.in2p3.fr>
Date:
Mon, 03 Apr 2006 11:54:51 +0200
To:
babardrc@slac.stanford.edu

Hello,

I had a look on the various alarms et status of the
HV epics panels. I spent some times looking at records definitions
in the database and made some tests friday.
Here are the results of my investigations.

They are many status records on the various epics panels concerning our
HV system.
From the top, on the ODC main panel, we have DRC:X:X:X:STAT.
This records checks many things (Gas, FEE, Wiener crates...) but amongst them
we have a HV records DRC::HV:PS:STAT.
This is the records used in our main panel, "Monitor.dl", to put the High Voltage section
in red or green. This records has no alarm field attached to it, and only his value (.VAL)
can be checked.
When everything is fine, DRC::HV:PS:STAT is 0. It is 1 only if at least one full sector is OFF.
I verified friday that switching off, on one crate, 3 boards of one sector and 3 boards of the other one
has no effect. Except that the alh becomes crazy and completly red, nothing appears on the
Monitor.dl panel and only a "UnCnf" message on the 'caen.dl' panel.

Let's go now to the main HV panel, caen.dl.
When a single board is off, it can be seen on HV main panel (caen.dl) only
by "UnCnf" white label poping up under the 2 ON or OFF buttons.
It comes from the record DRC:SC_<crate>:HV:PS:ONOF switching from ON to OFF (...).
The sector status, given by DRC:SC_<sector>:HV:PS:STSTR,
stays at ON. This records comes to OFF if the 4 boards of the sector are OFF.
Note that this records is used to calculate the Runnable flag. We go to
Non Runnable bacause of this records when it goes to OFF or Tripped.
The other indicators, like DRC::HV:PS:OVV_CR<crate>, DRC::HV:PS:UNV_CR<crate> stays
always green...I guess they don't reflect the detector situation but the crate itself.
On the bottom of the panel, the board status with the green and red lights on a line,
with records DRC::HV:PS:CHK<board>_CR<crate> are just checking if the board is there...
Nothing happens to this records when the board is swiched off, ramps up or down.

So imagine we have one board off, you have an alarm on the alh, everything looks fine on the
Monitor.dl, and there is a small "UnCnf" message on caen.dl. You need to go to the board panel
to see more.
Here, the record DRC::HV:PS:STSTR_BD<crate>_<board> has the value OFF
but no alarm is attached to it.
Note that board status DRC::HV:PS:STSTR_BD<crate>_<board> and sector
status DRC:SC_<sector>:HV:PS:STSTR are correlated. When the voltage are
ramping up or down, you can see the 2 variables going to 'RDN' or 'UNV' (I could not see this
every time I was ramping a board, because the refreshing time from IR2 to Paris is sometimes
....long!).

To resume the situation, we have:
  - up to 3 boards off by sectors (whatever how many sectors are concerned), DIRC
is OK on ODCmain, we are runnable, HV looks OK on our main panel, some "UnCnf" messages
appear on the HV panel but the sector indicators stay at ON. You can see what's happening on the alh.
  - if (at least) one full sector is dead, then we go to Non Runnable, we are 'red' on Odcmain, HV is red
on the main epics panel and the sectors indicates 'OFF'.

I hope this answers some of yours questions about the HV alarm situation.


Christophe