Group" LABCOM

H. "Nakanishi

M. Kojima

M. Ohsuna

S. Hidekuma

S. Komada

National Institute for Fusion Science (NIFS-Repository)

§ 17. Preliminary Result of Online Operation of the LHD Data Acquisition and Manage-ment System Nakanishi, H., Kojima, M., Ohsuna, M., Komada, S., Hidekuma, S., LABCOM Group The LHD data acquisition and diagnostics control systems have started their operation along with the experimental se-quences. The first period of the LHD experoments began on Mar. 31 1998. To establish the cooperation with the LHD central control equipment, the timing signals of the experiment master se-quences S 1 ""' S 10 and some interlock lines are given to the diagnostic-related subsystems through the wired connections. The diagnostics control system has one master PLC (pro-grammable logic controller) to receive them, and the VME computer which manages it will read the signal status and re-distribute them toward the data acquistion systems through the network protocol "ONC RPC 4.0." Among the data acquisition server computers and their management computer, the experimental time sequences are notified as the timing events which will awaken the different processes in the data acquisition sequence. The CAMAC data acquisition, for instance, has two events of the setup and the initialization as the pre-trigger processing, and one acquisition in post-trigger. The transmission way of these timing events are implemented by using the network package named "HAR-NESS" which realizes the object-sharing virtual space among its participant computers. Its communication protocols are simply based on TCP/IP. The virtual shared memory package Harness is another presentation protocol layer we have applied for the data acquisition and management system, as shown in Fig. 1. While RPC provides a simple mechanism of giving and receiving messages, Harness makes the shared memory space among the invited participant computers where any kinds of experimental data objects can be shared simultaneously. As for the data retrieve, transfer, and store, remote and lo.cal clients can directly communicate with the experimental database servers. The LHD data acquisition system adopted the object-oriented database (OODB) and its management system (ODBMS) named "02 " due to the suitability for the object-oriented data handling manner which unifies the over-all system construction. The transactions between database management servers and clients are implemented by using the 0 2 bindings (i .e. computer language API), and so we ap-plied C++ for storing/retrieving data and Java for setup pa-rametes. These transactions can also be transferred on TCPIIP, while the language binding API provides higher-level access-ing functions which are independent of the network or trans-port protocols. Especially for the LHD data acquisition system, fast network connections are indispensable for the data cross-reference among the distributed server computers. It is be-cause they have to treat the huge amount of experimental data, and the typical amount of the rawdata in the second LHD ex-perimental period is considered to be up to a few 100 MB 138 _,---·----( Summarv ~ , Databa.1·;. / \ ~--~ / --.. -""' \_lt'WU• Sen-er! "--. _  _./ Fig. 1: Virtual shared memory system by HARNESS: It pro-vides the object sharing functions and the task process-ing synchronization. per each shot. As the fusion plasma experiments have the general tendency that experimental data transfers concentrate within a definite time period just after the discharge, the max-imum transfer rate in it are surely expected. Such character-istic is quite suitable to apply the impermanent point-to-point connection by means of a momentary circuit-switching tech-nology. As the fast switching network, we have adopted the 100Mbps FDDI-based switching equipments as the local con-nection for each data acquisition computer, and as a backbone of their network, applied a 622Mbps ATM. As the preliminary operation of the data acquisition system in the first term of the LHD experiment, we have applied the two kinds of CAMAC data acquisition ways; one is using the massively parallel processing (MPP) system as we considered to be the main system, while the other is the standalone test-bench system which can originally control the CAMAC sys-tems locally for the test use. The latter was auxiliary applied to supplement the treatment for the special devices or modules. The total amount of the acquired rawdata volume in each di-agnostics are listed in Table 1. Table 1: Acquired rawdata mass in 1st-cycle LHD expen-ment. (shot #1 ""'#1888) Diagnostics Data (MB) main/aux. Halpha 4,231 mam Millimeter wave 4,361 aux. Bolometer 8,276 aux .---+ main Fast Ion Gauge 1,825 mam ECH 3,380 aux. Impurity Monitor 2,169 main Magnetics 12,847 main/aux. Langmuir Probe 6,706 main Total 43,795 (ave.23 .2MB/shot) 

Preliminary Result of Online Operation of the LHD Data Acquisition and Management System

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