--
Mark M. Ito, Thomas Jefferson National Accelerator Facility
12000 Jefferson Ave., Mail Stop 12H, Newport News, VA 23606
Email: marki@jlab.org, Office: (757)269-7175, Pager: (757)680-7175
------------------------
Mark Ito
December 7, 1996
Version 2
CONTROLLING PMT HIGH VOLTAGES
We are presently using two different computers talking to two
different VME controllers (aka IOC's) to control HV for historical
reasons. cebafe will control beam counter and tagger channels and use
the IOC clasgas. clas10 will control the time-of-flight and
calorimeter channels and use IOC clas-sc8.
detectors HP workstation IOC
--------- -------------- ---
calorimeter/time-of-flight clas10 clas-sc8
beam/tagger cebafe clasgas
The following instructions are for the calorimeter/time-of-flight
(with the variations for beam/tagger shown in parentheses). The
control will be consolidated as soon as we have a chance.
Some useful information:
------------------------
HV will not be applied to a channel unless the appropriate mainframe
is "on" and the channel is "enabled" and the demand voltage has been
set to a non-zero value.
Voltages are in volts, currents are in micro-amperes and time is in
seconds. E. g., ramp up rates are in V/s.
A "mainframe" is a physical crate of cards that holds up to 16 HV cards
numbered 0-15.
A "HV card" controls 12 channels, numbered 0-11.
A "group" is a collection of HV channels that can be enabled and
disabled with a single command. Each group has an index which is
defined in the file $APP/hvca/db/ecsc.grp (bmta.grp).
There is a HV file which contains all HV control parameters and geographic
information: $APP/hvca/db/ecsc.dat (bmta.dat). The columns in this
file are:
channel label
group id
allow/disallow operator HV turn on: 1 for allow, 0 for disallow (not coded)
mainframe arcnet address
slot number
sub-module number: 02 for all PMT HV channels (as opposed to chamber HV)
channel number
demand voltage: a signed number
measured voltage dead zone: a significant change in voltage
measured current dead zone: a significant change in current
ramp up rate: unsigned
ramp down rate: unsigned
trip current: signed, should match sign of demand voltage
software "maximum": in volts (not yet implemented)
To start the gui:
-----------------
Log into clas10 (cebafe) as clasrun, using the standard password.
Set the DISPLAY environment variable:
setenv DISPLAY your_x_terminal_name:0.0
Give the command:
hv
To exit the program:
--------------------
De-iconify the "medme" icon.
Open the menu "File".
Click on "Exit".
Description of Screens:
-----------------------
Auxiliary screens are accessed by pushing the overlapping-squares-icon
buttons and choosing from the menu that appears. In a lot of cases the
menus have only one choice. Yes, this is redundant. It is a feature of
medm as far as we know.
To change a value place the cursor in the appropriate "set" box, type
in the desired value and hit <return>. You must hit <return> to enter
the value.
Main Screen
-----------
HV/On and HV/Off buttons: turn mainframe on and off. When off the
"LED" is white, when on it is green.
Group Enable/Disable: Enables (green) or disables (red) an entire
group. (Do not use, see "Trouble Shooting" below).
Save: Will save current values of the set and measured voltages and the
measured current. (Do not use, see "Trouble Shooting" below).
Restore: Will initialize all values using those contained in the HV
file. (Do not use, see "Trouble Shooting" below).
Alarms: Not yet implemented.
Links to Voltage/Current: Calls up screens that display measured and
demand voltages and measured currents. The labels are those of the
first channel displayed on a page. Each page contains up to 24
channels.
Voltage/Current Screen
----------------------
Enable/Disable: Enables (green) or disables (red) an individual
channel. If a channel is enabled, a green "LED" turns on.
Set Voltage: field for inputing a new demand voltage. Must be a signed
number.
Voltage/Current: Same as "Links to Voltage/Current" on main screen.
Control Parameters: Calls up screens of the control parameters not
shown on the Voltage/Current screen.
Trouble Shooting
----------------
Rebooting an IOC
----------------
The current version of the software is having problems doing
simultaneous operations on large groups of channels. The symptoms are
that certain fields that should update their values do not. The
classic example is the measured voltage not changing, even after the
demand voltage is changed and the channel has indeed gone to the new
value. For this reason certain of the buttons mentioned above should
be avoided for now if at all possible. We are currently working on a
solution to this bug.
If the system seems to be corrupted and you are getting the behavior
mentioned above, you can often recover by rebooting the VME
controller, which in EPICS is called an IOC (Input/Output
Controller). Here's the drill:
For the calorimeter/time-of-flight (beam/tagger):
Exit medm. On the small "medme" screen select "File" and then "Exit".
log into clas-sc8 (clasgas) as marki
telnet clas-sc8 (telnet clasgas)
VxWorks login: marki
Password: the-usual-password
Reboot the IOC. There will be a delay after you issue the following
command and your carriage return will not be echoed.
reboot
Log back into the IOC. See above.
Load the software. The first character of the command is the less-than
sign, "<".
< clas-sc8.load (< clasgas.load)
The loading will take a couple of minutes. You should look for a
message saying that the initialization of the cache is complete, one
message for each mainframe.
Start medm again.
Taking Mainframe 3 Out of the Loop
------------------------------
The calorimeter mainframe #3 has been acting flaky. Occasionally, it
has taken itself off line and taken the communication to the others
along with it. The only way to reset it is to go down into the hall
and cycle power. Please call an expert to do this. While waiting for
the access, you can control the other two mainframes on the forward
carriage. To do this:
Log into cebafe as clasrun (yes, that's cebafe even though the forward
carriage is controlled from clas10).
Change the database file that will be use by giving the command:
remove_mainframe_3
Reboot clas-sc8 by following the procedure given above. Note in
that procedure that you must be logged into clas10 (a HP workstation)
in order to telnet to clas-sc8 (an IOC).
To add mainframe 3 back in, type (from clasrun's home directory on
cebafe, as in the remove step) the command:
add_mainframe_3
and then reboot the clas-sc8.
Problems?
---------
name office pager home email
---- ------ ----- ---- -----
Mark Ito 7175 680-7175 249-4472 marki@jlab.org
Sasha Philips 5199 none (703)525-4704 philips@gwis2.circ.gwu.edu
(202)994-8228 <--(office at GWU, your best bet)
Bonnie Madre 7059 680-7159