Java Based Data Monitoring and Management System for LHD
M. Emoto, M. Shoji, S. Yamaguchi, National Institute for Fusion Science, Toki 509-5292, JapanJ. Kariya, Yamaguchi University, Ube 755-8611, Japan
H. Okumura, Matsusaka University, Matsusaka 515-8511, Japan
Y. Teramachi, University of Industrial Technology, Sagamihara 229-1196, JapanAbstract

2.1 Data Management Menu

We developed a Java based experiment monitoring andmanagement system DODAS (Databased Open DataAcquisition System) for LHD(Large Helical Device) atNIFS(National Institute for Fusion Science). This system
is based on the two key concepts “database” and “open”.
“Database” means that system maintenance facility andexperiment monitoring facility are integrated in order toguarantee correct experimental conditions.
“Open” means that the realtime data are shared among
distributed computers on the network for load sharing andincorporating new data processing ideas.

1 INTRODUCTION
This system is developed for the LHD in NIFS. It canmonitor many slow and real-time data such as such astemperatures of the vacuum vessel and the divertors, thecurrents and voltages of the superconducting magnets, thepressures and flow rate of the liquid helium and so on. It
also gathers many fast sampling data with the slow data inthe same time in same ADCs (Analog-Degital Converter).
The number of ADC can be expanded easily and isavailable up to 4000 channels.
This system is an extended version of the prototype
system [1]. In the present state, the system is continuously
recording 512 channels of data in 1Hz and records 64
channels of data in 1kHz while the experiment. The
number of ADC channels will be doubled in the future.
There are so many measuring data, the most important
things are how to maintain correct experiment conditions
and how to many members attend to the experiment andmonitor the data.
Therefor we developed the system on the keyword“database” and “open” by Java language. We adopted
Java because it is adequate for developing distributed
open system and rapid, reliable programming.

2 DATABASE
The information and controls of the system arecentralized to the database. The functions of the databaseare shown bellow by the menu titles. They are grouped to3 parts.

•••••••••••••••••••

User Registration
Purchase
Data Acquisition Front
LHD ComponentLocation of Sensor Registration
Measuring Item
Shield Box
Power Supply for Amplifier in shield box
Power Supply Tag for Amplifier
Power Supply Tag Assign for Amplifier
Power Supply for Sensor
Power Supply Tag for Sensor
Power Supply Tag Assign for Sensor
AmplifierAmplifier Tag
Amplifier Tag AssignSensor PurchaseSensor Conversion Table
Virtual Tag Registration

2.2 Experiment Set up Menu••••••

Tag Monitoring
Experimental Registration
Connection Search
ADC Control
System Configuration MaintenanceQuench Set up

2.3 Experiment Control Menu•••••••••

Experiment Selection
Experiment NoteExperiment Member Registration
Experiment Status Control
Slow Sampling
Fast Sampling
Realtime Monitor
Slow Data Search
Fast Data Search

2.4 Features of the database
As shown in the above menu, we want to manage
everything in the database as far as possible. Now it keeps

information of the components such as amplifiers, sensors,connections between them, and others to maintain theLHD status.
The tags are designed to represent everything andattached to the components of the LHD. For example, themenu “Virtual Tag Assignment” means to assign tag tothe high-level measurement quantity that is derived bycomputing other measured quantities. If a tag is used in adocument, we can know that from which quantity thequantity was derived and with which sensor, amplifier and
ADC it was measured.
In the “Experiment Note” menu, the experiment
members write memos in the applet window, whichusually was written in the personal notes. These memos
are time stamped, related to the experiment and saved in
the database. The members share the collected and timethreaded memos written by all members and know wholeaspect of the experiment.
In the “Tag Monitoring” menu, we can set the upperand lower bounds of tag values. The system monitors
those values and when it finds out of range value, it sends
e-mail and telephones alarm to the staff.

3 OPEN SYSTEM
The system collects data and provides them in the formof strip charts applet [Fig. 2] to the members in realtime.
Because there are so many data, the system has notenough performance to provide simultaneously every data.
Therefore we must introduce some mechanism of loadsharing.
The data acquisition machine, in which ADC interface
board is equipped, sends realtime data in multicast packets.
Any machine on the segment can be a client of the dataserver and it receives these packets and processes the data.

The acquisition machine itself is one of the clients. It
receives raw data and compute high level quantities.
Another client is a data saver and it periodically creates
saved data files. The web server can access these files by
NFS (Network File System).
Provided that 1) on the 10BASE ethernet dedicated to
the realtime data transfer, 2) running the receiver programin the realtime scheduling class on a SPARCstation 2, theexperiment [2] showed that the program can receive 800
packets/sec with 1040 bytes length packet. The transfertime from the sender to the receiver is 3msec.
It is a useful way to use a network as a realtime databus. If we use a gigabit ethernet and high performancemachines, we may send 10kHz realtime data.

4 DEVELOPMENT BY JAVA
We developed the system by Java language, because
Java is adequate to develop reliable distributed systems.
Due to the security of JDK1.1, the Web server, RMI
daemon and database server run on the same machine.
The programs on the data acquisition machine directly
control the ADC device, so they are written in C language.
In order not to lost realtime data, the data acquisition
machine is separated from the Web server and only fixedjobs run on it. As shown in Fig. 1, device control
messages such a “start ADC” are sent from applet to RMI
daemon by RMI (Remote Method Invocation), and sent to
C language interface by JNI (Java Native Interface), thensent to the Data acquisition machine by RPC (RemoteProcedure Call).

5 PLAN•

Developing data client programs.

fast sampling

NFS

datafilename

ADC

RAID

Data Acquisition

System Control

Raw Data Sender
RPC

Virtual Tag Sender

JNIslow samplingraw data

Database Server
JDC
RMI daemon

Web Serverhigh-level data
RMI

Multicast packet

data

data definition

Data Client
Figure1: System configuration

controlethernetdata

Web Clientapplet

We install the data client programs to the distributed
machines on the network data bus, so that all of data canbe shown at the same time.
•Adaptive setting of bounds of tag values according tothe stage of LHD control.
We can know the unexpected statuses more early, so
we can do finer control of LHD.

REFERENCES[1] S. Yamaguchi et al., J. Plasma Fusion Res. 73, 335(1997). (in Japanese)[2] J. Kariya et al., J. Plasma Fusion Res. 74, 67 (1998).
(in Japanese)

Figure2: Real-time Graph