JAERI-Conf 95-021

3a3-4
CONTROL SYSTEM FOR THE JAERI TANDEM ACCELERATOR
Susumu HANASHIMA
Department of Reactor Engineering, Japan Atomic Energy Research Institute,Tokai, Ibaraki, Japan

Abstract
A new control system for the JAERI
tandem accelerator has been developed
using concurrent programming and multi
processor technology.
There are eighttransputers in the syste~ including
front end processors of CAMAC serial
highways.
Thispaper
reports
anexperience of the development and theoperation of the system.
1. Introduction
The JAERI tandem accelerator[!] had
beencontrolledbya
traditional
minicomputer since 1979.
However, we

had some difficulties to stay on the oldbase.
They are the difficulty inmaintenance of the old-fashioned computerand shortage of the computing power fora further expansion of the system. So,
we have developed a new control system
to replace old one.
In the new system we use concurrent
processing technology using multiple
microprocessors.
In a logical aspect,a control of a particle accelerator isa set of various processes controlling
and/or monitoring many control objects,
that is to say, accelerator devices.
Those
processes
arenotstrongly
coupling each other and have logicalconcurrency.
This implies that theHost system

Accelerator devices
Fig. I Block diagram of the new control system for the JAERI tandem accelerator-436-

JAERI-Conf 95-021

control system is a good field of
application of concurrent processing
technology. Using multiple processors,a merit of concurrent processing isenhanced in the system performance.
2. Overview of the System
The control system is usingtransputer[2] and concurrent processing
systemthecallWe
technology.
Figure 1 shows a block
ACCELL[ 3].
The newdiagram of the new system.
usingsystem
host1)aofsystem consists
system,centrala2)
a work station,3)serial highway drivers, 4)a CAMAC
serial highway system[ 4, 5] and 5) two
personal computers. The main roles of
the host system are to support executionof the central system and to work as apart of a man-machine interface. Dataof the central system needed to control
the accelerator are loaded from thehost. A bit map display of the host isembedded in the operator console of theaccelerator. Programs based on X-window
system[6] are used on the display.
Connection to the central system is anINMOS link[2] and a S-bus link adapter.
The host system is also used as a fileserver. The central system is a multi
processor of four T800 transputers [ 2]with local memory of one mega bytes toIt works as a main
16 mega bytes.
element of data processing. We canchange number of transputers to optimize
The serialloads of transputers.
highway drivers are front end processorsof the central system to CAMAC system.
Transputers are also used in thedrivers. They have charge of low level
control of the CAMAC serial highways.
CAMAC serial highway system is almostNineteen
the same as the old system.
CAMAC crates are distributed on the four
serial highways. Two of the crates arededicated to the control console. Theassignablehasconsole
controlwhich are called shaft
valuators,
dedicatedandassignableencoders,
meters etc. to control and monitor datapoints. Programming languages for thetransputers are parallel C(INMOS ANSIC)[?] and OCCAM2[8,9]. Programs of thetheondeveloped
aretransputers
personal computers. They are also usedfor monitoring a system operation.

3. Early Experience of Operation andImprovement of the System
The first version of the new system
had started daily operation for theaccelerator control in October of 1992.
The reliability of the system has been
ofp~:~rformance
But,
good enough.
message transfer between concurrent
processes in the system was not so good
as expected. In the system, messages
areprocesses
application
betweentransferred through processes named
monitors.
In October of 1993, the performanceof the message transfer was greatly
improved from about 2 milliseconds toabout 0. 3 milliseconds pe•r one message
In the work, We analyzed
transfer.
program execution times of several
instructions of the transputer and used
new programming technic for betterSo we could make theperformance.
improvement without any change ofexternal specifications of the monitors.
A new function of linked control
using a virtual data points[3] was
The virtual
tested in March of 1994.
data point named final E•nergy(Ef) andits control process, scaling process,It waswere installed in the test.
intended to work as that a change of Ef
reflects to several data points by thescaling rule[10] process, in the mannerthat beam transport of the accelerated
particle is maintained and the final
energy is set equal to se1:ting value of
The mechanism follov~s not only toEf.
a step of the change but also to thecontinuous change of the virtual data
point. Some mismatch between valuatorsof the control console and the newfunction was found by the test. On theother hand, it was shown that system
performance of message passing andsmoothcalculation was enough foroperation. Introduction of the function
into daily machine operation should besuspended till improvement of thevaluators.
4. Development of the Concurrent Program
We have used OCCAM and Parallel ANSIC as programming language. Concurrent
programming
usenables
programming
through natural modeling of the target-437-JAERI-Conf 95-021

system that has intrinsic concurrency.
It is a most important advantage of theconcurrent programming.
On th'e other
hand, programming of the concurrent
system has only a limited length ofhistory
inapracticalworld.
Methodology of the programming is notwell known yet. Especially, there is aproblem about a deadlock in the world ofconcurrent programming.
It is asituationinwhich
two(ormore)
processes mutually wait for the otherprocess to become ready to receive
messagesand theprocesses
cannotexecute farther operations.
A smallmistake in the programming introduces
probabilityofthedeadlock.
Programmers sometimes cannot follow
action of the system where several
processes running concurrently.
We
needed training different from usual
sequential programming. We met several
additionaldifficulties
about
development tools etc. In spite of thedifficulties, the concept of concurrent
programming has been attractive one.

[9]INMOS Limited, OCCAM2 Reference
Manual, Prentice Hall, 1988.
[10]S.Hanashima and E.Minehara, Scalingof the optical parameters for theJAERI tandem accelerator,
Rev.Sci.Instrum., 57(5), 1986,
p787-788.

References[1]M.Maruyama, Proc. 3rd Int. Symp. on
Electrostatic Accelerator
Technology, Ork Ridge,Tennessee(1981),p17.
[2]INMOS Limited, The Transputer Data
Book 2nd Edition, Prentice Hall,
1989.

[3]S. Hanashima et.al., The control
system for the JAERI tandem particle
accelerator using transputers,
Transputer and OCCAM engineering
series Vol . 35 (Proceedings of the5th Transputer/Occam international
conference 1993 Osaka, Japan) IOS
Press, p69-81.
[4]IEEE Inc., Modular Instrumentation
and Digital Interface System(CAMAC),
IEEE Std 595-1976.
[S]IEEE Inc., Serial Highway Interface
System(CAMAC), IEEE Std 595-1976.
[6]0.Jones, Introduction to The X Window
System, Prentice Hall Inc., 1989.
[7]INMOS Limited, ANSI C toolset user
manual, !NMOS Limited 72 TDS 22400,
1990.
[8]INMOS Limited, Transputer Development
System 2nd Edition Prentice Hall Inc.

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