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\begin{foil}{ExoGam Data Acquisition}
\subsubsection*{Midas}

\begin{itemize}
\item \begin{bf} M \end{bf} multiple
\item \begin{bf} I \end{bf} instance
\item \begin{bf} D \end{bf} data
\item \begin{bf} A \end{bf} acquisition
\item \begin{bf} S \end{bf} system
\end{itemize}

Application Independent Components
\begin{itemize}
\item Graphical Interface
\item Network Interface
\item Spectrum Interface
\end{itemize}

Application Specific Components
\begin {itemize}
\item Data processing
\end {itemize}

\end{foil}

\begin{foil}{ExoGam Data Acquisition}
\subsubsection*{Midas - Graphical Interface}

Experiment control and monitoring 

Diagnostics

Data analysis 

\begin{itemize}
\item Quick and easy to generate Motif compatible Graphical User Interface
\item Designed for use in many varying configurations by a distributed group of implementors
\item Common look and feel across all components of the system
\item Easy to add new components and safely allows "user" additions and local modifications
\item May be extended without sensible limit
\end{itemize}

\end{foil}

\begin{foil}{ExoGam Data Acquisition}
\subsubsection*{Midas - Network Interface}


Network Interface via Register Server - network distributed objects

Allows the GUI to control and monitor the state of the data acquisition
equipment and real-time software components


\begin{itemize}
\item VXI objects
\item VME objects
\item CAMAC objects
\item software objects (variables and procedures)
\end{itemize}

The GUI can access all objects (or a selected set) of a given catagory
by a single built-in procedure call

\end{foil}


\begin{foil}{ExoGam Data Acquisition}
\subsubsection*{Network Objects}

May be dynamically created

Access can use a wide range of "wild card" features

An object can be

\begin{itemize}
\item  Hardware register or control within VXI or CAMAC module - addressible to
a single bit level
\item  Portion of VME address space - single location or block
\item  Variable within control processor software
\item  Procedure within control processor software
\item  Any action linked to specific class and object
\end{itemize}


\end{foil}
\begin{foil}{ExoGam Data Acquisition}
\subsubsection*{CAMAC}
 
The following CAMAC ADC modules are currently supported by the
Midas package
 
\begin{itemize}
\item LeCroy 4300B ADC
\item Silena 4418/V ADC 
\item Ortec 413 ADC
\item Ortec 811 ADC
\item Ganelec QDC1612F
\end{itemize}

Also the following LeCroy CAMAC modules

LC2277    LC2551    LC4208    LC4413    LC4415A    LC4434
LC4504    LC4516    LC4518    LC4532    LC2375


\end{foil}

\begin{foil}{ExoGam Data Acquisition}
\subsubsection*{Midas - Spectrum Interface}


Location independent software interface

\begin{itemize}
\item  Hardware histograms - real-time "singles" - from data on DT32 bus
\item  Software histograms - on-line data analysis
\item  Offline and Stored disc based histograms
\end{itemize}

Multiple servers (possibly of different type) may appear as one to the GUI


\end{foil}

\begin{foil}{ExoGam Data Acquisition}
\subsubsection*{Electronics}

Following Eurogam structure

\begin{itemize}
\item Primary detectors interfaced via VXI electronics

\item Ancillary detectors may have VXI electronics

\item Ancillary detectors may use CAMAC adcs with FERA readout interfaced
via the FERA => VXI module (Euroball/Diamant/Bordeaux)

\item Eurogam/Euroball Hardware Histogrammer

\item Single DT32 bus data source into D2VB module (Eurogam) in VME

\end{itemize}


\end{foil}

\begin{foil}{ExoGam Data Acquisition}
\subsubsection*{VXI control}

Each VXI crate contains a Slot 0 (Resource Manager) module (Struck) 
which has inbuilt a standard VME CPU board. This communicates with the Midas
control GUI via ethernet and allows setup and monitoring of all VXI modules
in the crate. A logic analyser facility is built-in which can monitor
some VXI backplane lines.

Each VXI crate contains a Readout Controller module (Struck STR 8080) which 
contains a DSP. In addition to code to handle normal readout extensive
diagnostic and test facilities are built-in. These allow diagnostics
to locate faults within the VXI crate and data generation features to
aid system testing.


\end{foil}

\begin{foil}{ExoGam Data Acquisition}
\subsubsection*{Event Processing}

Single data stream (follows Eurogam) - hardware event building via
DT32 bus.

\begin{itemize}
\item  Data received via D2VB module (DT32 bus master; 2Mbyte fast RAM; buffer list processing)
\item  Software checks data for quality; correct format and valid contents
\item  Reformat to output data format (Eurogam, Euroball or different?)
\item  Send to Tape Server via high speed broadcast network (fddi or fast ethernet)
\item  Produce at each step statistical information for monitoring
purposes
\item  At all stages data buffers accessible to GUI for diagnostics
\end{itemize}


\end{foil}

\begin{foil}{ExoGam Data Acquisition}
\subsubsection*{Tape Server}

Manages all output devices

\begin{itemize}
\item  Exabyte
\item  Digital Linear Tape (DLT)
\item  Other SCSI devices ??
\end{itemize}

Features

\begin{itemize}
\item Multiple logical data streams
\item A data stream may span several output devices
\item Online data stream duplication (same data written to several devices)
\item Drive performance monitored and available to GUI
\end{itemize}

\end{foil}


\begin{foil}{ExoGam Data Acquisition}
\subsubsection*{Online Analysis}

Event blocks sent via the data network from Event Processor to  Tape Server
are available in "spy" mode to any number of workstations.

\begin{itemize}
\item  "Spy" on the online data 

non intrusive 

cannot effect main task of getting data to tape
\item  "User" programs running in standard workstations
\item  Multiple concurrent data analyses possible
\item  Library subroutines allow histograms to be created for viewing using the Midas Spectrum Viewer
\end{itemize}


\end{foil}

\begin{foil}{ExoGam Data Acquisition}
\subsubsection*{Electronics}

Following Euroball structure - multiple data sources

\begin{itemize}
\item VXI and FERA via VXI with Hardware Histogrammer as before

\item Muliple DT32 bus data sources into D2VB modules (Eurogam) in VME

\item Ancillary detectors also use CAMAC adcs with FERA readout interfaced
directly to D2VB/HSM

\item Other data acquisition systems feeding 16/32 bit ECL bus interfaced
via D2VB/HSM or similar can be handled


\end{itemize}

\end{foil}

\begin{foil}{ExoGam Data Acquisition}
\subsubsection*{Electronics}

multiple data sources

Additional requirements

\begin{itemize}
\item Each data source must tag each event fragment with a global event number

\item All data sources must be synchronised so that the data blocks from each data source contain fragments of the same events

\end{itemize}

\end{foil}

\begin{foil}{ExoGam Data Acquisition}
\subsubsection*{Event Building}

multiple data sources require that software merge the event fragments to generate complete events

\begin{itemize}
\item Check raw data streams

\item Convert from specific raw formats to standard

FERA - convert VSN/subaddress to group/item

\item Generate singles histograms

\item Merge event fragments using the global event number tag

\end{itemize}

Other processing as for a single data source

\end{foil}

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