Information on the Reaction Chamber "JBUS" Buffer
	     
	     
	     Septembre 1998
	     
	     

This documentation concerns the reading and testing of "JBUS" buffers coming from
the reaction chamber PC controler.

These buffers are read from the PC by the VME and sent to the Acquisition Cluster.

Information can also be obtained from the Acquisition manual (Chapter 3) on the 
Ganil Web site.

                    http://ganinfo.in2p3.fr/acquisition

                         ------------------------------
To launch the JBUS buffer operation, one should execute the file :

                           ACQ_INIT_VME.VMECMD
   
(in directory DISK$USER:[EGSI.GANACQ_MANIP.EGSI])

This should be done at the begining of the experiment or when a reboot (of the
VME) is done. A "VME JBUS INFO" from GAG_CMD>  will inform you of the status of
the system.

                         ------------------------------

At the VME level :

Different instructions can be given on the VME screen, exemple :

8:>JBUS TIMER 10 (in seconds)

8:>JBUS READ

8:>JBUS INFO

8:>JBUS SET 1 3499 20   (where 20 is the number of words readin the PC)

8:>JBUS START

8:>JBUS STOP

All these instructions can be given form the VAX acquisition by (example) 

GAG cmd> VME JBUS TIMER 10


For managing the Jbus reading, instruction are found in the following files
(in directory DISK$USER:[EGSI.GANACQ_MANIP.EGSI]) :

ACQ_INIT_VME.VMECMD

ACQ_FIRST_IN_RUN.VMECMD

ACQ_END_RUN.VMECMD


                         ------------------------------

In the Acquisition control program (acq_ctrl_user_egsi.for), one finds :

This part will read "on line" the Jbus buffer and write it on disk

c
c --- Bloc JBUS
c
        delay=10
        option=0
        iretour=acq_store_jbus_buffer(delay,option)
        if (iretour.lt.0) then
!           call acq_send_reply('ERREUR buffer JBUS')

           write (6,'(1x,/,a,/)') 'Erreur JBUS, status =', iretour
        endif

This buffer is written in :

D_ACQ_INDRA:[EGSI.ACQUISITION.RUN]ACQ_JBUS_BUFFER.DAT

This disk buffer can then be read and dumped on the screen by the program :
          DISK$GANIN5_USER:[EGSI.JBUS.SLOW_TEST]TEST_READ_JBUS_BUFFER
          
          on the Ganin5 Workstation
          
One can also dump it by :

          dump/dec/blocks=(start:1,end:1)/word ACQ_JBUS_BUFFER.DAT

                         ------------------------------
The format of the Buffer is (in french !!!, obtained from the Web site):

Les buffers JBUS ont la structure suivante : 

     - structure de type JBUS_HEAD 
     - distance vers le prochain ordre jbus (UNSINT16) 
     - ordre jbus compose de mots de 16 bits :
         numero d'automate 
         adresse de debut 
         nombre de mots lus 
         mot lu 
         . 
         . 
         . 
         . 
         mot lu
     - distance vers le prochain ordre jbus (UNSINT16) 
     - ordre jbus compose de mots de 16 bits :
         numero d'automate 
         adresse de debut 
         nombre de mots lus 
         mot lu 
         . 
         . 
         mot lu
     - 0000 fin de buffer
     
     
     
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Eric Plagnol