JLab discriminator

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There is a Hall-B page for JLab discriminator


Manual for 16-Channel Discriminator/Scaler VME Module (by J.Proffit), 20-Nov-2002, in (pdf)
Manual for New 16-Channel Discriminator/Scaler VME Module (draft by Ben Raydo), 6-Mar-2009, in (pdf)
Manual for New 16-Channel Discriminator/Scaler VME Module (rev.B by Ben Raydo), 28-May-2010, in (pdf)
Manual for New 16-Channel Discriminator/Scaler VME Module (rev.C by Ben Raydo), 11-Feb-2011, in (pdf)

Linux VME support

Brian Moffit from CODA group has setup a directory for software for Intel based VME controllers running Linux. README there is a good introduction to the subject.


RPMs for VME controllers running Linux located in the directory


Available files are:

gefvme-kmod-common-4.1-0.i386.rpm (Development files)
kmod-gefvme-PAE*.rpm (Kernel module)

To install the development RPM without kernel module will require the --nodeps option

rpm -i --nodeps gefvme-kmod-common-4.1-0.i386.rpm

A simple example program using driver by Brian Moffit

#include "dsc2.h"
int main(){
 vmeOpenDefaultWindows(); /* Map the VME bus memory (For Linux only.). */
 dsc2Init(0xe00000,0,1);  /* Base memory: Only last 2 HW switches are relevant, 
                             the rest are lost due to shift of address. */
                          /* Memory size per board. */
                          /* Number of boards. */
 dsc2Status(0,0);         /* Board number and flag which is not used. */
 dsc2PrintScalers(0,0xff);/* Board number and printing option */

Installation and usage

The software is part of Hall-D epics configuration. It could be downloaded using the following command:

svn co https://halldsvn.jlab.org/repos/trunk/controls/epics

From there make sure You have these 2 directories.


Of course it is better to download the whole epics directory and You'll have the environment configuration and EPICS If You don't have those directories use svn to check them out (i.e. svn co <URL>). Then You should compile using make command.

Scalers readout preliminary driver

There is also document in the DocDB which complements the information here. It might be downloaded from https://halldweb.jlab.org/doc-public/DocDB/ShowDocument?docid=1877

The current scheme of data flow is the following (from top to down):

VME bus
mutex-ed access to the hardware
a separate thread to poll scalers every
second and stores them in the memory
EPICS Scan Task
will periodically start a record processing
will copy from memory and push to CA server
EPICS CA Server will broardcast

Other supplemental files are:

  • JLabDiscr_subMain.cpp -- The standard main program
  • JLabDiscr_subConfig.c -- hooks for EPICS
  • JLabDiscr_subConfig.dbd, JLabDiscr_subrecord.dbd -- DBD files
  • dbJLabDiscr.db -- DB file

The output

The output is accessible via PV hallddisc1:JLabDiscr. It has a type of aSubRecord.

Its INPA field setups the card number (Will be configured once during IOC initilaztion).
The VALA is an array of 16 contains scalers of gated triggers.
The VALB is an array of 16 contains scalers of gated TDC values.
The VALC is an array of 16 contains scalers of ungated triggers.
The VALD is an array of 16 contains scalers of ungated TDC values.
The VALE is a signle scalers of gated reference clock.
The VALF is a signle scalers of ungated reference clock.


NOTE: The location of files and installation instructions are subject to change. Check back frequently to check the most up-to-date information.

Files are in the directory and subsequent directories: /group/halld/Online/controls/epics/app_nerses

place for include make files
Boot configurations for IOC-es
Boot configuration directory for JLab Discriminator. The boot configuration is in the file st.cmd
Installed DB files directory. Original files are from *App/Db directory.
Installed DBD files directory. Original files are from *App/src directory.
Installed binaries
Installed libraries
Development source files
Original DB files directory