\documentclass{chowto}

\title{Operation of the Caen High Voltage System}
\howtotype{user} % ``expert'', ``user'', ``reference''
%\experiment{Name of experiment} % Optional
\author{H. Fenker}
\category{general} % Subject area of this document

%\maintainer{Name of person maintaining document} % Optional
\date{April 4, 2003} % Can use \today as the argument

\begin{document}

\begin{abstract}
This manual describes how to operate the Caen High Voltage system in 
Hall-C from both the front panel and from the GUI.
 \end{abstract}


\section{Related {\it Howtos}} 
The following Hall-C {\it Howto} documents may be helpful.

%--DELETE THOSE  DOCUMENTS MENTIONED HERE WHICH ARE IRRELEVANT
User Level Documents-
    \par \indent \indent Monitoring SOS ``Utilities'' Systems \cite{howto:sos_detector_monitoring}
    \par \indent \indent Monitoring HMS ``Utilities'' Systems \cite{howto:hms_detector_monitoring}
    \par \indent \indent Base Equipment Checklist \cite{howto:base_equip_checklist}

Expert Level Documents-
    \par \indent \indent Starting Up and Shutting Down the SOS Detectors \cite{howto:turn_on_sos}
    \par \indent \indent Starting Up and Shutting Down the HMS Detectors \cite{howto:turn_on_hms}
    \par \indent \indent Operating the Hall-C Flammable Gas Leak Detector System \cite{howto:flam_gas_sensors}

Reference Documents-
    \par \indent \indent Detector Signal and High Voltage Cable Map \cite{howto:cable_map}
    \par \indent \indent SOS Drift Chamber High Voltage and Signal Connections \cite{howto:hms_drift_map}
    \par \indent \indent HMS Drift Chamber High Voltage and Signal Connections \cite{howto:sos_drift_map}
    \par \indent \indent SOS Nominal Settings: Voltages, Currents, Flows, etc. \cite{howto:sos_nominals}
    \par \indent \indent HMS Nominal Settings: Voltages, Currents, Flows, etc. \cite{howto:hms_nominals}


\section{Normal HV Operation - using the Graphical User Interface}
\subsection{Starting the Control Screens}
The detector High Voltages are set from the X terminal (hallcxt13)
just to the right of the center of the main control console. This X
terminal should normally be logged on to {\tt cdaqh1} with the {\tt cvxwrks}
account.

After logging on, control screens for the HMS and the SOS must be
started. Click the left mouse button anywhere on the screen background
and select the ``HMS HV'' menu item and repeat for the ``SOS HV''
item. The control screens will take several seconds to start up. (If a
screen fails to appear after 2 minutes, reboot vmec1 for HMS or vmec6
for SOS, wait 5 minutes and try starting the screen again. If necessary,
the control screens may also be started step-by-step as follows
\begin{enumerate}
\item {\it Open an xterm window on cdaqh1.}
\item \%cd \$EPHHV {\it \{for HMS, or} \$EPSHV {\it for SOS\}}
\item \%cd tk
\item \%hv.tcl
\item {\it After several seconds the GUI screen will be displayed.}
\end{enumerate}

\begin{figure}[h!]
\centering
\includegraphics[width=\textwidth]{CAEN_HV_operation-HVGUI.eps}
\caption{ A snapshot of the SOS Main High-voltage GUI Screen
\label{fig:SOS_HV_GUI}}
\end{figure}

\subsection{Operation}
The operation of the HMS and SOS HV screens is menu driven.
The main GUI window includes a pair of histogram-style charts, with each
bar indicating the readback voltage or current for a channel.
It also provides drop-down menus and two control buttons.

To turn on or modify the high voltage, use the ``Group'' menu to pull up 
a control screen for the desired detector subsystem. A
global ON option exists for each ``group''. (There is no ON button
that turns on all the high voltage for the whole spectrometer.) Turning
on the high voltage will set the voltage last stored in the Caen High
Voltage mainframes. If these voltages are incorrect, they can be set
with the group screens, or the restore menu item on the main screen
may be used to retrieve a previous set of high voltage settings. To
set a new operating voltage, click the cursor in the {\tt Vset} box
of the appropriate channel and change the entry to the desired setpoint.
Be certain to press {\tt Enter}  while the cursor is still in the box
in order to actually enter the new voltage. Similar
changes may be made to the trip current (Itrip), maximum allowed voltage
(Vmax), and the Ramp-Up and Ramp-Down rates (Volts per second).

\subsubsection{GUI Menu Items}
\begin{itemize}
\item File
	\begin{itemize}
	\item {\bf Backup} {\it Initiates a {\tt Backup} of the current settings}
	\item {\bf Restore} {\it Starts a {\tt Restore} of saved settings.}
	\item {\bf Quit} {\it Terminates the GUI}
	\end {itemize}
\item Command
	\begin{itemize}
	\item {\bf Trip RESET} {\it Resets all {\tt Tripped} channels. Use freely.}
	\item {\bf IDLE} {\it Stops the GUI's communication with the HV supplies}
	\item {\bf unIDLE} {\it Restarts the communication with power supplies}
	\item {\bf IDLE} beep ON/OFF {\it Start/Stop audible IDLE warning}
	\item {\bf TRIP} beep ON/OFF {\it Start/Stop audible TRIP warning}
	\end{itemize}
\item Group
	\begin{itemize}
	\item One entry for each detector group presently defined. Select the one
you want to manipulate.
	\end{itemize}
\end{itemize}

\subsubsection{GUI Buttons}
\begin{itemize}
	\item {\bf HV OFF} {\it Turn off all high voltage channels}
	\item {\bf Silence/Unsilence} {\it Press to silence or unsilence the audible alarm}
\end{itemize}

\subsection{Monitoring the Status and Resetting Trips}

The column labeled ``Vset'' contains the setpoint for the voltage, and
the column labeled ``Vmon'' contains the actual voltage as read back
from the power supply. The ``Imon'' column contains the current drawn
by the channel. The ``Status'' column shows whether the channel
voltage is actually set or not. Occasionally a channel may trip off
for some reason. This is indicated by the word ``Tripped'' in the
Status column. To correct this, select {\bf Trip Reset} under the
{\bf Command} menu.

The GUI includes a system to automatically monitor the status of all
channels. When not silenced, an audible alarm will sound if any of the
high voltage channels is found with a voltage far away from its
setpoint. {\bf This alarm feature should never be silenced unless an
operator is manually monitoring the high voltages!} The yellow button
on the GUI should always read {\tt Silence}, indicating that the
silence function has not been selected. Channels which
are in alarm state are listed on the bottom line of the main GUI
window. They are identified in the format {\tt hv\_CR\_CH}, where {\tt
CR} is the Caen crate number and {\tt CH} is the high voltage channel
number. If necessary to identify the bad channel(s), you can refer to
the automatically generated high voltage map files {\tt
\$EPHHV/perl/channel\_map} and {\tt \$EPSHV/perl/channel\_map}
discussed in references \cite{howto:cable_map}.

\subsection{Backup and Restore}
If permanent changes are made to the high voltages, these new settings
should be saved with the {\bf Backup} menu item. Similarly, you can
{\bf Restore} setpoints that have previously been backed up.  Note:
Backup and restore operations take an extremely long time (several
minutes).


\section{Caen Power Supply Operation from the Front Panel}

Modifications to the parameter settings should in general not be made
at the front panel or through a locally connected terminal if the
EPICS system is in operation. This mode of control is meant for
diagnostics and testing of a detector system prior to running. There
are only two features which must be set at the front panel before
initiating an EPICS control session - the crate number and the
RS232 configuration (suggested
defaults are 9600 baud, no parity, 1 stop bit).

If unfamiliar with the operation of the HV system in local mode, one
should get experienced personnel or review  Chapter 4 of the
Caen Technical Information Manual \cite{howto:CAEN_HV_TechMan}.
Operation is generally straightforward, however. Use the arrow
and menu buttons to get the desired channel on the LCD display,
then use the arrow buttons to select the parameter you wish to
change. Use the {\tt Modify} and {\tt Change} menu items to initiate
the change; use arrows or numeric keypad to set the new value.
To turn a channel {\tt ON}, for example, display the channel, 
move the cursor over the word {\tt OFF}, and press {\tt MODIFY}.

\section{Outside Influences}
Each Caen mainframe has an {\it Interlock} input on the front
panel which may be used to disable high voltage output unless desired
external conditions are satisfied. For example, if the gas
system is in alarm the wire chamber high voltage will be shut off.
Because they share a common crate, the high voltage supplies for
both the HMS Gas \v{C} erenkov counter and the HMS drift chambers
will be disabled. If you discover that you cannot get certain high
voltage channels to come up, try to find out if they are interlocked.

\end{document}

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% $Log: CAEN_HV_operation.tex,v $
% Revision 1.1  2003/04/04 16:02:59  saw
% Initial Checkin
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