COMPUTER CONTROL SYSTEM FOR THE SIAM PHOTON SOURCE
W. Pairsuwan, T. Ishii, National Synchrotron Research Center, Technopolis, Suranaree Universityof Technology, 111 University Avenue, Muang District, Nakhon Ratchasima 30000, Thailand
G. Isoyama, ISIR, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, JapanT. Yamakawa, Meisei University, Hotokubo, Hino, Tokyo 191-0042, Japan
Y. Hirata, Toshiba Corporation, 1-1-6 Uchisaiwai-cho, Chiyoda-ku, Tokyo 100-8510, Japan
T. Takeda, N. Tsuzuki, Fuchu Works, Toshiba Corporation, 1 Toshiba-cho, Fuchu,Tokyo 183-0057, JapanAbstract
A new computer control system is being developed forthe accelerator complex of the Siam Photon Laboratory,
which is the first synchrotron radiation facility underconstruction in Thailand. Basic ideas for the new control
system consisting of PCs and PLCs are described.

1 INTRODUCTION
The synchrotron radiation (SR) facility named the Siam
Photon Laboratory is being constructed at Nakhon
Ratchasima, which is about 250 km to the northeast
Bangkok, in Thailand [1]. The accelerator system for theSiam Photon Source, consisting of a 1 GeV electron
storage ring and an injector, was donated by the SORTEC
Laboratory in Tsukuba, Japan [2]. It was dismantled andits components have been transported to Thailand. The
building for the Laboratory is now under construction andthe accelerator system will be reassembled by the end of2000. The storage ring is upgraded from a dedicated SR
source for study of micro-lithography to one of thehighest-performance second-generation SR sources in theworld [3].
The hardware of the control system for the SORTEC
accelerator complex consisted of a mini-computer in thecontrol room as a control computer and several datastations at various locations in the accelerator complex, inwhich interface boards for controlled devices and a CPU
board were installed [4]. The control computer and thedata stations were linked with RS-232C lines. Since thedata transfer between the computer and the data stations
was slow, another control system using a UNIX
workstation and the VME interface was developed forcontrol of the storage ring during machine study, in which
the fast response of the control system was required. The
operating system (OS) for the mini-computer was special;
it is a combination of the UNIX operating system and areal time operating system. The control software waswritten in special FORTRAN running on it. The minicomputer was more than 15 years old and the special OS
has not been used any more, so that we cannot used eventhe control software. The interface boards are not standard
ones and CPU chips used in the CPU boards are notavailable now. All these factors made us decide to replace
the whole control system including the interface hardware.
The old control system was abandoned and a newcomputer control system will be installed for the Siam
Photon Source.
The new control system is now being designed. In thispaper, we will report the basic idea of the new control
system for the Siam Photon accelerator complex.

2 ACCELERATOR COMPLEX
The ground plan of the accelerator complex of the Siam
Photon Laboratory is shown in Fig. 1. It consists of a 1GeV electron storage ring for the SR source, a 1 GeV
synchrotron, a 40 MeV electron linac, a beam transportline from the linac to the synchrotron, which we call LBT,
and a beam transport line from the synchrotron to thestorage ring, HBT. The synchrotron and the linac are
installed in the underground room and the storage ring ison the ground floor. The electron beam accelerated withthe synchrotron is extracted and transported through theunderground tunnel, steered to the ground floor andinjected into the storage ring from inside.
The main parameters of the accelerator complex are
listed in Table 1. In the routine operation for user
experiments, the accelerator system will be operated asfollows. The electron beam will be injected into thestorage ring typically twice a day since the lifetime of theelectron beam is expected to be longer than 10 hours. The
injection time will be 10-20 minutes and consequently thesynchrotron, the linac and the beam transport lines standby most of the time. The electron energy of the storage
ring will be raised from 1 to 1.2 GeV in the future by
replacing the power supply for the bending magnets of thestorage ring. Since the maximum energy of thesynchrotron can not be made higher, the electron beam
will be accelerated in the storage ring after injection.

3 HARDWARE
The new control system should be cost effective. Thevery fast response time is not required because such time
critical jobs are made by using hardware circuits. We,therefore, have decided to use personal computers ascontrol computers and programmable logic controllers(PLC) as interfaces to controlled devices. The basic ideasof the hardware for the new control system are as follows.
- Defacto standard components.
- Distributed control system.
- Multi-layered structure.
- Device control station (DCS) for each subsystem.
- Cutting down wiring.
The control system is being designed based on thesebasic ideas. The structure of the hardware system isshown in Fig. 2. It has two layers. The accelerator
complex will be divided into five subsystems; they are thedevices in the control room, LBT, the synchrotron, theelectrical substation for the synchrotron, and the storage
ring. A DCS or a few DCSs will be installed for eachsubsystem. Four PCs at first and the DCSs are connectedwith Ethernet. We call this level the information layer. ADCS includes a PLC or some PLCs. The majority of thecontrolled devices are power supplies for magnets andthey have parallel I/Os. In order to cut down wiring

Experimental Hall

between controlled devices and DCSs, a remote input andoutput station (RIO), which converts parallel I/O signals
to serial signals, will be installed near every controlled
device. We plan to incorporate RIOs in power supplies tobe newly made. A DCS and RIOs are serially connectedwith an optical cable, which is named the computer link.
This level is called the device layer.
We plan to adopt IBM-type PCs with Windows and
PLCs made by Allen Bradley, because not only they aredefacto standards but also they are easily available inThailand.

4 SOFTWARE
The operating system for the PCs will be Windows NT
4.0 and the control software will be written in JAVA or C.
The control software in the PLCs will be written in thestandard ladder language.
The principal functions of the control system for the SR
source are threefold; (i) automatic operation triggered bya single crick for routine operation to provide SR for user
experiments, (ii) control of individual power supplies
mainly used in the commissioning of the accelerator
system as well as in machine study, and (iii) monitoring
and logging of the accelerator status. Since the accelerator
complex for the SR source will be operated in various
modes to meet requirements of SR users, the control
software should be flexible enough to meet theserequirements, especially in the automatic operation mode.
We will use a similar method developed at UVSOR
facility of the Institute for Molecular Science [5].
In the automatic operation for user experiments, theaccelerator complex will be operated as shown in Fig. 3.
The accelerators can be divided into two groups in thiscase; the storage ring and the injector including the linac,
Table 1: Main parameters of the accelerator complex.

Storage Ring

High Energy BeamTransport LineInjector Linac

Booster
Synchrotron
Low Energy BeamTransport LineFig. 1. Ground plan of the accelerator complex of theSiam Photon Laboratory.

Storage ring
EnergyCircumferenceStored current (expected)
Magnet lattice
Superperiodicity
Long straight sections
Natural emittanceRF frequency
Harmonic number
Synchrotron
EnergyCircumference
Beam current
Repetition rate
RF frequency
Harmonic number
Linac
EnergyRF frequency
Beam current
Macropule width
Energy spread (FWHM)
Emittance

1.0 GeV
81.3 m
500 mA
DBA
47m×474 π nm rad
118 MHz161.0 GeV
43.19 m
30 mA
1.25 Hz118 MHz740 MeV
2.856 GHz
60-80 mA
1.7 µs1.3 %0.7 π µm rad

PC(Windows-NT4.0)
MMIS 1MMIS 2Printer

DCS

Timing
System1

Control Room Device Control StationInclude Global Interlock)
HBT Beam
Stopper OpenStatus

Sy Fast
Kicker P/SON

Sy Septum
P/S ON

AdmittanceControl System
Normal Status

Door Close
StatusBeam Line
Shutter Close
StatusEmergency
Stop OFFStatus

Timing
System2

Radiation Safety
Monitor System
Normal Status

Beam Monitor
Controller

Ethernet

ScreenMonitorSlit 1,2

DCS
Synchrotron
Device Control Station

Beam Stopper
Controller
Gate Valve

RIO

VacuumController

RIO

RIO

QD Power
SupplyRIOQF Power
SupplyCavity Temp.
Controller

VacuumController

RIO

RIO

RIO

RIO
Ext. Septum M
Power Supply
RIO
Fast Kicker M
Power Supply

RIO: Remote IO Station
DCS: Device Control Station

RIO
St Magnet (H)Power Supply

Inj. Septum
Magnet Power

Trigger

RIO
St Magnet (V)Power Supply

RIORIOSt M Power
SupplyRIO

RIO

Bump Magnet
Power Supply

QF Power
SupplyQF Magnet
Power Supply

RIO

RIO

QD Power
SupplyRIO

HBT BM
Power Supply
HBT BM
Power Supply
HBT QDPower Supply
HBT QF
Power Supply
HBT StH
Power Supply

Q1 Power
SupplyQ2 Power
SupplyQ3 Power
SupplyQ4 Power
SupplyRIO

RIOSt M Power
Supply 8

RIO
St M Power
Supply 9RIO

RIO

RIO

RIOBump M Power
Supply(1)ScreenMonitor
RIO

Bump M Power
Supply(2)Correction CoilPower Supply 3

Gate Valve
RIO

VacuumGauge

Bump M PowerSupply(3)RIO
Correction CoilPower Supply 4

RIO

RIO

RIO

RF Power
SupplyRIOSt Magnet
Power Supply 6

RIO
Bending M
Power Supply

VacuumController

Correction CoilPower Supply 5

RIO
Bending M
Power Supply

RIO

RIO
Quadrupole M
Power supply

RF P/S
Controller
RIO

St Magnet
Power Supply 7

VacuumController
RIO

RIO

RIO

RFKO
RIO

Septum M
Power Supply

Correction CoilPower Supply 2

RIO

BeamStopper

St M Power
Supply 11

RIORIODCCTRIO

St M Power
Supply 10

Correction CoilPower Supply 1

RIO

Beam Position
Monitor
RIO

RIO

RIO

HBT StV
Power Supply

Linac
Controller

Computer link

RIOInterlock
DevicePattern

Pattern
MemoryStorage Ring Device Control Station

BM Power
SupplyBM Main CoilPower Supply

QD Magnet
Power Supply

RF Power
Supply 1

DCS

RIO

RIO

Tuner
Controller

BM Power
SupplyDCSElectrical Sub Station
Device Control Station
Computer link

Computer link

Computer link

LBT
Device Control Station

Computer link

DCS

Timing
SystemRIO

Tuner
Controller

RIO
Quadrupole M
Power Supply

Fig. 2. Structure of the control system.
LBT, the synchrotron and HBT. In the shutdown mode,the storage ring and the injector are all switched off. In
the ready mode, all the magnets in the both system except
for pulse magnets for injection or extraction are excited
but the electron beam is not accelerated by the injector. In
the injection mode, the electron beam is accelerated fromthe linac and injected into the storage ring. Finally in theoperation mode, the storage ring is operated as it is or theelectron beam is accelerated in the storage ring in thefuture, but the injector is put in the standby mode, inwhich the power supplies in the injector system areswitched on but the magnets are not excited. Accordingly
the automatic operation should have the following
commands; (a) start-up and shutdown, (b) injection

Fig. 3. Commands and statuses of the accelerator complex
in the automatic operation.

start/stop, (c) acceleration/prepare for the next injection.
In the control software, each command has an option
number, specifying a data file in which names of data files
for set vales are written. This makes it possible to operate
the accelerator complex in various operation modes
without changing the control software.

REFERENCES[1] W. Pairsuwan and T. Ishii, “Siam PhotonLaboratory”, J. Synchrotron Rad. 5 (1998) 1173.
[2] M. Kodaira, N. Awaji, T. Kishimoto, H. Usami andM. Watanabe, “Development of Highly Stable
Synchrotron Radiation Source at SORTEC”, Jpn. J.
Appl. Phys. 30 (1991) 3043.
[3] P. Kengkan, W. Pairsuwan, G. Isoyama, T.
Yamakawa and T. Ishii, “Magnet lattice for the Siam
Photon Source”, J. Synchrotron Rad. 5 (1998) 348.
[4] M. Takanaka, T. Iida, A. Komine, N. Awaji, S.
Nakamura, S. Nakamura, M. Ohno, “Control system
for the 1 GeV synchrotron radiation source at
SORTEC”, Proc. 2nd EPAC, Vol. 1 (1990) 836.
[5] N. Kanaya, H. Hama, J. Yamazaki, O. Matsudo andG. Isoyama, “Control system capable of gracefully
degraded operation for the 750 MeV synchrotron
radiation source”, IEEE Trans. Nucl. Sci. 40 (1993)
1286.