The 9th Symposium on Accelerator &ience and Technology, Tsukuba, Japan1993

Present Status of Device Controls and Hardware Interfaces
for the RCNP Ring Cyclotron
T. Yamazaki, K. Tamura, K. Hosono, T. Itahashi, M. Kibayashi,
I. Miura, K. Nagayama, T. Saito, A. Shimizu, M. Uraki and H. Ogata
Research Center for Nuclear Physics, Osaka University
Mihogaoka 10-1, Ibaraki, Osaka 567

Abstract

combination of mails requires that many tasks must be resident in the main memory at the same time. If the capacity
Since the first proton beam from the injector AVF of the main memory is insufficient, frequent swappings ofcyclotron was injected to the ring cyclotron in 1991, the tasks may occur. This reduces the computer performance,computer control system has been used for the beam accel- and at last the control system becomes to hang up. To
eration of the ring cyclotron. Some device control modules overcome this situation a system tuning of the operating
have been updated, and computer configuration has been system was tried. In 1992 the SCU main computer was rechanged in 1992. Total control system performs basic facil- placed VAX 4000/200 computer with main memory of 48
ities almost satisfactory under actual cyclotron operation. M bytes. The system become stable since and the controlsystem hangup seldom occurs.
I. INTRODUCTION
By communicating with 94 UDCs (universal devicecontrollers) the RING-GCU subcomputer covers theThe control system for the RCNP ring cyclotron wasdesigned in 1987, [1,2,3] and the constructions of con- controls of injection beam line, cyclotron magnets andtrol hardware units and softwares were completed in 1990. injection-extraction system. By communicating with 98
Total control system was installed in the ring cyclotron UDCs the BT-GCU subcomputer covers the controls ofbuilding in 1990, and adjustments and operational tests of magnets of the beam line. By communicating with 59
devices were executed from the local control panels con- UDCs the DIAG-GCU subcomputer covers the control ofnected to the universal device controllers located near the beam diagnostic devices. The RF-GCU subcomputer covered the controls of RF system, vacuum system and coolingdevices.[4]system,and this GCU subcomputer communicated withThe universal device controllers are connected to submanyUDCs(i.e. 182 UDCs). New VACCOL-GCU subcomputers with optical fiber cables, and the subcomputers
are connected to the main computer with an Ethernet ca- computer was added to cover the controls of vacuum sysble. Total control system was operated from the console tem and cooling system by communicating with 84 UDCs.
displays of sub computers and the central operator console Consequently the RF-GCU subcomputer now covers theconnected to the main computer. The hardwired interlock controls of RF system including beam buncher located insequences, the control sequences of startup-shutdown-fault the injection beam line, and communicates with 98 UDCs.
processes stored in subcomputers, and databases that de- Now two micro VAX II computers are used as RING- andscribes many characteristics of control items were updated RF-GCU, and three RTVAX 1000 computers are used asbased on valuable experiences of actual operations under · VACCOL-, BT- and DIAG-GCU.
various conditions.
III. UNIVERSAL DEVICE CONTROLLER
Proton beam from the injector AVF cyclotron was injected to the ring cyclotron and accelerated in 1991. TheDuring long-time operation of the ring cyclotron somecomputer control system is now used under almost satisUDCs
become to unable to control from the SCU main
factory conditions for the beam acceleration of the ring
computer and central operator console. This phenomena
cyclotron. [5]occur only for UDCs installed on the basement of the ring
cyclotron vault. For example, the UDCs for the controls
II. CONTROL COMPUTER NETWORKof power supplies of trim coils and phase-voltage tuning
The computer network of the control system of the controls of the accelerating cavities of RF system become
RCNP ring cyclotron and associated beam lines started to uncontrollable. By resetting UDC board manually inwith a main computer (a system control unit SCU using the cyclotron vault this UDC becomes to controllable frommicro VAX 3500 computer with main memory of 16 M the main computer again. Lines on the UDC boards seembytes) and four subcomputers (group control units GCUs to suffer from a kind of noise created nearby. By adding
using a micro VAX II computer and three diskless RTVAX noise artificially to a UDC board one can reproduce sim1000 computers with main memory of 9 M bytes).
ilar phenomena and this noise seems at least one of theThe control program in the SCU main computer con- origins. The processor chip on the UDC is Intel 8344 misists of 30 tasks. One task initiates another task or per- crocontroller and has 192-byte dual-port RAM on the chip.
foms each operation by receiving adequate mails (requests After examining the ROM firmware of the UDC some dataor data) from other tasks. Rapid operations of the central areas were moved from external RAM to internal RAM. If
operator console may generate many mails in a short time, the noise disturbes the signal around the processor chip,and sometimes the number of mails becomes overflow. A this countermeasure may reduce the hangup of the UDCs.

-68-After replacing the firmware ROM chips of UDCs in thecyclotron vault with revised ones the hangup of the UDCs
is avoided.
IV. LOCAL CONTROL PANEL OF UDC
The control cabinets are located in the cyclotron vault,
power supply area and experimental halls, and contain control units and drive units. A control unit contains UDCs,
local control panels, relay cards, analog-to-digital convertercards, multiplexer cards and interface cards for drivingstepping motors and AC servomotors. A drive unit contains driver modules for stepping motors.
A local control panel is prepared for the direct control
of a UDC. The firmware of a UDC contains many tasks,
and task7 task in the firmware starts at 100 ms intervals
for the local control panel. The panel has push-butomswitches with lamps, LED indicators and a liquid-crystal
numeric display. The functions of these elements are determined by the contents of task7 task, and are slightly
different depending on the types of control units.
The standard usage of LED indicators is the status
display of interlock conditions. The status data are stored
in a communication register (CRG) area of the UDC. Only
the limited important data, that are useful for the maintenance purposes of the UDC and device itself, are displayedon LED indicators. In case of power supplies the contentsof CRG were fixed at the construction time, and therefore
the contents of the local control panels are also unchanged.
External interlock conditions may change during actual usages of power supplies. However the CRG of a power supply has only one bit for the external conditions and details
are left to the CRG of the interlock system. The controls ofRF systems are complicated, and all the informations were
not always prepared at the design stage. Additional informations became to necessary at the adjustments of RF
power amplifiers and accelerating cavities, and the local
control panels were modified upon these requests. Someinterlock items are added to the LED indicators after adetailed examinations on the actual control operations ofconcerned device.
The liquid-crystal display shows preset and actual values of the control parameter (magnetic-coil current, highvoltage, position of stepping motor, etc.), and contents ofCRG, input and output ports of UDC. The preset and actual values are stored in CRG as binary forms and units
convenient for the device control. In case of the power
supply the maximum of preset and actual values in UDC
corresponds to the upper-limit current or voltage. In caseof the stepping motor preset and actual values in CRG
show the numbers of stepping pulses. These preset andactual values in CRG are converted to values in physicalunits (A, kV or mm) and display at liquid-crystal display.
The firmware of UDC allows quadratic transformation forthese conversions. However now only linear transformationis adopted. The same conversion coefficients are used at
the main computer and the central operator console.
The local control panels are useful for the maintenanceof UDCs and related modules. However the UDCs of vacuum and cooling systems have no local control panel. Local control cabinets of vacuum and cooling systems havegraphic status display panels in addition to UDCs, andmost informations stored in UDCs are available from indicators of these graphic display panels and control switches.
If one needs the contents of input and output ports ofUDCs, portable local control panels may become necessary in future.
V. INTERLOCK SYSTEM
The control unit for interlock system contains a UDC,
relay cards and a local control panel. The interlock conditions are inputted to input ports of UDC and are also
used in hardware interlock system through relay boards.
The results of software interlocks obtained from soft wares
are outputted to output ports of UDC from SCU maincomputer and GCU subcomputers, and are used in hardware interlock system through relay cards. The contentsof input and output ports of UDC are displayed on LED
indicators of the local control panel through CRG dataof UDC. Whenever new devices are added to the ring cyclotron and associated beam lines, new interlock items areadded to the control units of interlock system. Input andoutput ports and relay cards of the interlock system canfunction as common relay input-output devices, and areused as general status displays such as operation states of
AVF cyclotron and device states that belong to groups ofother subcomputers.
The interlock system also communicates with the radiation protection system and the building control systems
that open and shut doors and rotary shutters on beamlines. Restricting the control objects to the power supplies
and motors the hardwired interlock system is rather simple. The standard control system was designed for these
purposes and it is easy to include their interlock conditions as software. However, the control system of the radiation protection system was designed by different manufacture and different principles, and many patches wereexecuted on hardwired parts after finding undesirable functions. Consequently the hardwired interlock parts as theinterface become complicated ones.
VI. POWER SUPPLY OF MAGNET COIL
A control unit of the power supply of magnet coils
contains a UDC, a 12-bit analog-to-digital converter and arelay card as the inputs of external interlock signals. The
setting values of magnet currents have accuracy of 16 bits.
Compared with this setting accuracy the measuring accuracy of 12 bits is insufficient for magnet control. The
standard control units of power supplies were originally designed as 12-bit current controls by the manufacturer, andwe had no room for choice at design stage. During particle
acceleration the beam profile of the extracted beam varies
due to the changes of acceleration conditions, and this instability influences to the quality of the measured dataof nuclear reactions. To watch long term drift of magnetic
field of the cyclotron magnets more accurate measurementsof the trim-coil currents become necessary. In addition tothis standard control system a current logging system bycurrent recorder is in progress.
In case of 400-MeV proton acceleration the vertical betatron frequency approaches to one and the beam current
reduces at larger radius. To keep the beam on the median-69-

plane and avoid vertical diversion it is necessary to gener- two-speed mechanism because its driving distance is large.
ate a symmetrical vertical magnetic field disribution. The When the beam current is measured as a function of raauxiliary coils of the cyclotron magnets are used for the dius, slow speed is selected. When the main probe moves
corrections of magnetic field distribution, and one can give to retracted position or to the starting position of meadifferent current to each auxiliary coil. By adding a small surement, fast speed is selected. The UDC controls thepower supply to an auxiliary coil, the vertical magnetic probe position directly for slow drive. For rapid drive thefield distribution can be modified. The computer interface UDC sets only the final position to a driver interface, andof power supplies adopted for this purpose was GP-IB or the driver interface controls the probe position by a hardRS-232C interface. Both GP-IB and RS-232C interfaces ware logic. Moreover the main probe has two measuring
are already adopted as the sub boards of UDC modules for modes, automatic and manual modes. For automatic mode
NMR field measurements and vacuum gauges, and the con- the probe measures the beam current from inner preset ratents of their firmwares may be applied to the control of dius to outer preset radius in sequential order. For manualmode an operator moves the probe to adequate radius andthis power supply with some modifications.
measures the beam current. Therefore there exists severalVII. MOTOR CONTROL
combinations of operations from the central operator console. Sometimes the main probe became uncontrollable
The stepping motors are used for the open controls during the probe operation at early acceleration period.
of the positions of electrostatic channels, frequency tuning Thereafter some operation sequences were inhibited by thedevices of RF power amplifiers and cavities, variable width software of the SCU main computer and the operations ofslits, beam probes and beam profile monitors.
interface driver module was reexamined. Now the unconThe stepping motor has no present position value, and trollable phenomenon of the main probe seldom occurs.
the pulse value corresponding to the present position isstored as the CRG data in RAM memories of UDC andIX. CONCLUSION
the GCU subcomputer. Because the RAM memories arevolatile, the position data must be stored in nonvolatile
The control system has improved remarkedly based
memory at power-off time of UDC and the GCU subcom- on the experience of actual cyclotron operations. Someputers. A command that stores these RAM data to a disk beam diagnostic devices has been added and undesirable
file of the SCU main computer is supported.
parts have been replaced or updated. Basic facilities ofSome position controls of RF cavities use AC servo- the control system become to operate almost satisfactomotors with a closed loop control. The closed loop control rily. Several efforts are now focused on the stable supply
method was chosen for devices that need large torque to of good quality beams from the injector AVF cyclotron todrive. It was not known at the design stage whether the the target position in the experimental halls.
closed loop control is adequate or not for particular deX. REFERENCE
vices. If it turns out that a device drived by AC servomotor
has very small position tolerance and the servomechanism
cannot reach to final stable state, one must change the AC [1] T. Yamazaki, et al., "Design of Control System for
RCNP Ring Cyclotron," Proc. 6th Symp. on Acceleraservomotor to a stepping motor with large torque. One AC
tor Science and Technology, Tokyo, 1987, pp.251-252.
servomotor of the RF system was changed to a stepping
motor for this reason.
(2] T. Yamazaki, et al., "Design of Distributed Control System for the RCNP Ring Cyclotron," Proc. 12th Inti.
VIII. BEAM DIAGNOSTIC DEVICEConf. on Cyclotrons and Their Applications, Berlin,Germany, 1989, pp.252-256.
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Technology, Osaka, 1989, pp.255-257.
tic devices has many functions. Some function requires[4]T.
Yamazaki,
et al., "Construction of Computer Conprompt response, but another function does not requirefor
RCNP Ring Cyclotron I. Hardware,"trolSystemsevere response. Therefore it is necessary to share more
Proc. 8th Symp. on Accelerator Science and TechnolCPU time for the functions that require severe time reogy, Saitama, 1991, pp.359-361.
sponse and use two displays effectively. After this improve[5]T. Yamazaki, et al., "Construction and System Tuning
ment the simultaneous controls of beam diagnostic devicesof Control System for the RCNP Ring Cyclotron andbecome easier.
Beam Lines," Proc. 13th Inti. Conf. on Cyclotrons andAt earlier stage of beam accelerations there was onlyTheirApplications, Vancouver, Canada, -1992, pp.672one three-wire beam profile monitor near the extraction
675.
radius of the ring cyclotron, and manual adjustment ofbeam extraction process was rather difficult. Therefore
two three-wire beam profile monitors were added at thebeam extraction radius and different angles. Simultaneousor successive measurements by these profile monitors candetermine the orbits near the extraction radius.
Main probe can measure radial beam profile from injection radius to extraction radius.~ The main probe has-70-