STATUS OF THE KEKB ACCELERATOR CONTROL SYSTEMDEVELOPMENT
T. Katoh, T. Mimashi, T.T. Nakamura, N. Yamamoto, A. Akiyama, S. Araki,T. Kawamoto, K. Komada, K. Kudo, T. Naitoh, T. Takashima and S. Kurokawa
KEK, National Laboratory for High Energy Physics
1-1 Oho, Tsukuba-shi, Ibaraki-ken 305, JapanIN TRODU CTIONKEKB is a 5-year project started in 1994 to convert the existing TRISTAN electron-positron accelerator/collider
into an asymmetric one.[1] TRISTAN is a three-stage cascade accelerator/storage ring with a 2.5Gev electron/positron
injector Linac, 8GeV Accumulation Ring (AR) and 33GeV accelerator/collider Main Ring (MR). For the KEKB project theLinac will be upgraded to provide intense 8GeV electron and 3.5GeV positron beams to inject directly into the KEKB rings.
The KEKB rings, the High Energy Ring (HER) and the Low Energy Ring (LER), will be installed side by side in thetunnel where the TRISTAN MR is at present. The TRISTAN MR will be shut down at the end of 1995 and the equipment
will be removed from the MR tunnel. As the 8GeV AR will not be used by KEKB, it will be used as a synchrotron lightsource and for accelerator experiments. At present, TRISTAN is controlled by a system using mini-computers and CAMAC[2], but modern technologies will be introduced for KEKB controls. To save money and manpower, the CAMAC system
will be reused after rearrangement. The present control system for TRISTAN was designed about 15 years ago and has
become very hard to maintain. It is clearly important to have a good control system for a modern intense beam asymmetriccollider. The quality of the control system required by KEKB is much higher and the quantity greater than that of thepresent system. However, the progress in the fields of computer hardware and software seems to give us the chance to havea more sophisticated control system and to make it possible for us to construct a control system which satisfies
requirements in both quality and quantity. The preliminary design has been reported previously [4].

FU N CTION AL REQU IREMEN TS
The control system design must be looked at from as many points of view as possible. Usually the suppliersof the system and the users tend to have different points of view. Therefore, we first started to review functional
requirements of the control system for the KEKB collider. The hardware groups that install the accelerator components tobe controlled want to monitor magnet current values, voltages of the power supplies and so forth, and if a failure occurs
they want it to be reported and recorded as soon as possible. The operations group wants the recording of the operations
sequence of the collider and to have tools to analyze the previous operations and make correlations between parameters andmeasured values for tuning purposes. Accelerator physicists need the connection between beam monitoring, simulation andbeam correction systems. The controls group itself has its requirements.
The principal functional requirements are as follows:
1) All the data that can be taken should be taken.
2) All the data taken should be saved for later analysis3) All the operations should be recorded for later inspection.
4) All the machine parameters and data about the machine components should be saved in the database.
5) The control system should be operator-friendly.
6) The programming system for application programs should be programmer-friendly.
7) The overall response time to an operator's request should be less than a few seconds, ideally one second,
unless the progress of the process is indicated.
CONS TRAINTSThe KEKB collider is a reconstructed machine and there are many constraints in constructing its control systemeconomically and effectively. The first of them is CAMAC. We have already accumulated a large number of CAMAC
modules in the TRISTAN control system and CAMAC is still thought to be the only well-defined standard for interface
modules which can be used for process input/output. The old mini-computers will be removed from MR sub-control
buildings and the CAMAC equipment configuration will be redone and some new CAMAC modules will be added. On theother hand, there is no constraint to introducing a new software environment, because all the application programs will benew.

The final commissioning of KEKB is scheduled to take place in 1998, so the control system should be installedat least one year before then. The basic system for the hardware and software development will be installed at the beginningof 1997. It will include some workstations, VME computers and X-terminals for the operator’s consoles. Anotherconstraint is that there are only a dozen people in the KEKB controls group.

BAS IC DES IGN CON CEPTS
Considering the requirements stated above and the restrictive conditions, the basic concepts are to use:
1) the so-called Standard Model for the accelerator control system.
2) international standards for the interfaces between the three layers, to facilitate later upgrading and maintenance.
3) international standards such as CAMAC, VME, VXI and GPIB as the interfaces between the control systemand the equipment to be controlled.
4) products either from international collaborations or that are commercially available, to minimize themanpower and effort required5) the object-oriented technique or abstraction to hide the hardware from application programmers,6) high-speed networks to connect the computers with each other to get a quick response,7) the linkmen system as in the construction of the TRISTAN control system, in which the linkmen make theequipment database and code device drivers for the application programs because they know the equipment best.
Finally, we decided to use EPICS as the KEKB control system environment, and we joined the EPICScollaboration.

S YS TEM ARCHITECTU RE
The control computer system is divided into three layers - presentation layer, equipment control layer and device
interface layer, as shown in Figure 1. The first two layers are divided functionally but connected with each other through ahigh-speed network such as FDDI. This is because the network traffic between the presentation layer and equipment control
layer computers is expected to be dominant. There is also a possibility of adopting a distributed shared-memory network toobtain fast data transfer and event transmission among the computers. The presentation layer which is called an Operator
Interface (OPI) in the EPICS world is composed of several workstations and about 6 to 10 X-terminals used as operator
consoles. The functions which the workstations run can be executed by a UNIX server which has multiple processors. Themain network is an FDDI ring that has a node at each local control building; there will also be an Ethernet segment in eachbuilding. The equipment control layer consists of about 60 to 80 VME Input/Output Controllers (IOC) distributed aroundthe KEKB rings. Each IOC will be allocated to a hardware group to avoid conflicts among groups or users. The final layer,the device interface layer, has standard modules such as CAMAC, GPIB, VXI, etc. There will be a special interface forcontrolling the magnet power supplies.
Pres ent at i on Lay er
OPI, the presentation layer, will include operators consoles, database manager, simulation computer, alarm
generation/recording, data logging, display and a gateway to the KEK in-site network. There will be workstations running
UNIX. X Windows, MS Windows and Windows NT are candidates for the operators console. The database manager
computer will keep all the information concerning KEKB including machine parameters, equipment specifications, location,and so on. The simulation computer will be used for accelerator physics simulation calculations for such purposes as orbit
correction. Faults in the equipment will be monitored by each IOC and reported to the alarm computer for broadcasting andrecording purposes. The data logging computer will collect data from various equipment control computers for later
analyses. The display computer will display data and transmit information over the KEKB site through the CATV networkand other media. There will also be a gateway computer to connect the KEKB control computer network with the KEK
laboratory network to make it possible for the accelerator department staff to reach KEKB collider equipment from theiroffices.
The software environment required for this layer is very important for the whole system. The fundamental
functions: to display status and measured values graphically, to control each piece of equipment etc., should be supported
from the start of installation of the machine equipment. The programmer-friendly interfaces must be provided for theaccelerator physicists to make application programs easily. And it is also important to have a very efficient data retrieval
and analysis system via the database.

Equi pm ent C ont rol Lay er
The equipment control layer consists of IOCs that functionally control the equipment of each hardware group.
Each IOC is a VME computer equipped with CAMAC serial highway drivers and other standard field-bus driver modules.
The operating system for the equipment control computer is VxWorks. The type of processor on the VME processor board
is not yet fixed and can be changed according to the requirements. The minimum requirement is that there must be a crossdevelopment system which runs on a workstation.
Dev i ce Int erface Lay er
There will be several field-buses for the lowest device interface layer. There are CAMAC crates and CAMAC
modules which can be re-used from TRISTAN. The CAMAC crates will be connected by CAMAC serial highways or
CAMAC branch highways according to requirements. There will also be other standard field bus equipment such as GPIB.
VXI modules will be used for the beam position monitors and fast signal measuring systems. There will be about 900
BPMs, and the electronics for them will be in the 20 sub-control rooms around the ring. Where the VXI system is used, itis planned to put a VME processor board into the VXI slot so that it can be used as an IOC. There are about 1900 beamsteering magnet power supplies installed in the four power supply rooms around the ring. These power supplies will becontrolled through a dedicated bus especially designed for them. A power supply control VME module will transmit parallel
control signals and the bus adapters will drive power supply controller modules as shown in Fig. 2.

CON CLU S IONThe KEKB control system is now in the final phase of design and the specifications are being defined. The firstsystem for development will be installed early in 1997; the construction will start at that time and should be finished by thesecond quarter of 1998. It seems essential to use commercially available products based upon standards and to make use ofsoftware sharing to reduce the manpower and effort required. The system should be friendly to the accelerator physicists whocreate application programs. The database will become the central core of the KEKB control system and will make itpossible to combine all the subsystems into one large system.

REFEREN CES[1] Shin-ichi Kurokawa, Status of TRISTAN-II Project, Proceedings of the 1993 Particle Accelerator Conf.,
pp. 2004-2006[2] Shin-ichi Kurokawa, et al., The TRISTAN Control System, Nucl. Instr. and Meth., A247, (1986) pp. 29-36.
[3] L.R. Dalesio, et al., EPICS Architecture, ICALEPCS 91, KEK Proceedings 92-15, (1992) pp. 278-282.
[4] T. Katoh, et al., “Control System Design for KEKB Accelerators”, Proc. 1995 Particle Accelerator Conference
and International Conference on High-Energy Accelerators, May 1 - 5, 1995, Dallas, Texas, U.S.A.