PLC Application in the Control of CIAE-30 Cyclotron
Li Zhenguo
China Institute of Atomic Energy
P.O. Box 275-3, Beijing, 102413, China

Abstract
Application of Programmable Logic Controller ( PLC )brings CIAE-30 compact cyclotron into entirely automatic
control, from cyclotron start-up until required beam current
obtained at target can be performed with a single function
key. The main parameters are sequentially set-up andregulated by PLC requiring no operators during routine
production. High anti-interference ability, reliable safety
interlocks, real time status monitoring and interchangeable
operation modes of either full or half-full control, makes
cyclotron reliable, stable, flexible and can display thedynamic status all the time. Processes of radioisotope
production, e.g. targetry, chemical analyses, radioactivity
monitoring and protection can be also performed with thesame PLC.
The cyclotron has been commissioned over the last twoyears and proved that the hardware arrangement andsoftware structure of the whole control system are practicaland successful.

transmission; excellent anti-interference; reliable safety
interlock.
The equipment interfaces, PLC and its peripherals buildup a complete control system and keep cyclotron always ina desired operation condition.
2 Hardware arrangement
The control hardware consists of two parts: PLC modules
and operation console. See fig.2.
PLC modules include: three CPUs (922R), one
coordinator (923C), a number of analog and logical I/Os,
one communication processor (CP527), one intelligentprocessor(IP241), special bus and internal supplies [2].
Operation console includes: a keyboard, a large highresolution colour monitor, two encoders, beam diagnosis
and a printer.

1 Relation between PLC and cyclotron
CIAE-30 compact cyclotron is a new kind of accelerator
dedicated to medical radio-isotope production. Its mainfeatures are compact structure, low power consumption,high beam intensity and easy change of energy. It consistsof complex equipment, e.g. external ion source, magnet,
R.F. generator, stripper, vacuum, water cooling, pneumaticactivator, transportation line, beam diagnostics, targetry
and various power supplies. The whole production processincludes H- beam production, acceleration, electron
stripping, extraction, focusing, transportation, targetcontrol, radioisotope analyses and sampling. Fig.1 showsthe main body of CIAE-30 cyclotron.
Automation of Cyclotron and production process need acompact and sophisticated control system to coordinate
these devices, to deal with sequence control, parametertuning, status display and human interface. The SIMATIC
S5-135U Programmable Logic Controller ( PLC ) waschosen due to that it is more suitable for the task,
especially, it can provide a simple and economic solution
to the logic control, process automation and statusmonitoring. Furthermore, its standardized hardware andprogram section make it easy to assemble and program.
In order to couple with the standard input and output
modules of PLC, special interfaces have be designed andadded to cyclotron equipment [1]. They have some common
specifications: sufficient electro-isolation ability; proper
logical signal level; high accuracy analog message

Fig.1 main body of CIAE-30 cyclotron.
PLC communicates with the cyclotron equipment
through the logical and analog I/Os, which translate orders
to and receive status messages from all the different
devices. The PLC communicates with the console throughthe communication and intelligent interfaces, which
receive operator instructions and transmit the processed
status signals to be displayed on the screen or printed onpaper. All analog parameters of the cyclotron can be
adjusted using the two encoders.

processing.
CIAE-30 cyclotron user program is divided into many
self-contained section blocks, called organization blocks(OB), program blocks (PB), function blocks (FB),
sequence blocks (SB) and data blocks (DB).
OBs provide the interface between system program andthe user program. PBs are used to structure the user
program into the hardware model. FBs are programming
units called frequently and repeatedly in complex functions.
SBs are special types of program blocks for sequencecascade. DBs are used to store data and texts.
These blocks can be 'nested' in the user program. Themaximum permissible nesting depth is 24 blocks.
The complete user program is divided into three partsand saved separately in three CPUs according to different
functions: logical, analog and communication. The threeCPUs operate in parallel and are synchronized by thecoordinator.
4 Operation features

Fig.2 hardware arrangement
Beam sensors are allocated along the beam path: axialinjection line, acceleration chamber, extraction,transportation line and targets. Beam signals are pretreatedby special interface circuits and then transmitted to thePLC for refreshing the storage and operation interlocks. In
the meantime, the pretreated beam signals are alsotransmitted to the beam monitor on the console to be
displayed simultaneously in three manners: digital, analog
and ratio.

The cyclotron status can be clearly graphically displayedon the monitor screen. These screens are called 'page's.
Every page not only displays the key parts of the different
systems, but also gives the real time dynamic messages bychanging colour or positions. Different pages also assign
different meanings to the function keys, according which
the operator can choose appropriate instructions to the PLC.
Fig.3 shows the page structure of the operation synopsis.
Two encoders can be assigned to any of the analog
parameters for tuning at any time. These parameters
directly determine the cyclotron specifications, e.g. beamenergy, intensity, extraction efficiency and ratio of thebeam distribution among different targets.

3 Software structure
The programming language of PLC used in CIAE-30
cyclotron is standard STEP-5 with four representations:ladder diagram (LAD), statement list (STL), control
system flowchart (CSF) and, specially for sequentialcontrol, GRAPH-5. The four representations are equivalentand the user can choose the programming method best
suited for control purposes [3].
Structured programming makes software user-friendly.
The program can be broken into clearly definedtechnology-related sections - thus simplifying program
development and modification. Standard function blocks
provide self-contained complex function sequences thatcan be inserted as required at any point in the program. It
makes programming simpler and quicker.
The complete program of the PLC consists of system
program and user program. The system program contains
all statements and declarations for internal function. It is
an integral part of PLC and can not be changed by the user.
The user program contains all statements and declarations
programmed by the user for signal and sequenceFig.3 page structureDifferent set of parameters can be stored into the PLC
library, which is able to contain up to 50 sets and any ofthem can called into operation when necessary, thatsignificantly saves machine tuning time and improves
operation efficiency.
The PLC can operate in two modes: full automation or
half automation. In the mode of full automation, thecyclotron can automatically start-up by pushing one
function key, including turn on power supplies, coolingwater, vacuum, set up the magnet, R.F., ion source step bystep and, put the strippers into correct positions, until thedesired beam is obtained on the target. In the mode of half
automation, the PLC divides the whole sequence into
different sections. At end of every section, operator
interventions are required but, the operation sequence andsafety interlock are also managed by the PLC. The fullautomation mode is suitable for routine production and thehalf automation mode is suitable for machine maintenanceand equipment test. The two modes can be transferred at
any time.
The CIAE-30 cyclotron and its PLC control system havebeen commissioned since 1995. More than two years ofoperation practice has proved that PLC application in thecontrol of cyclotron is user-friendly, flexible, reliable and,the hardware arrangement and software organization of thewhole control system are suitable and successful.
References
[1]
[2]
[3]

PLC Control system and Equipment interfaces ofCIAE-30 Cyclotron, Internal, CIAE.
Manual, S5-135U Programmable Controller,
SIEMENS.
STEP-5, Programming Package for Personal
Computer, SIEMENS.