H. Nakanishi, M. Kojima and S. Hidekuma


Distributed Processing and Network of Data Acquisition and Diagnostics Control for Large Helical Device (LHD)

Date of publication:

Nov. 1997

Key words:

LHD, distributed system, data acquisition, diagnostics control, VME, WindowsNT


The LHD (Large Helical Device) data processing system has been designed in order to deal with the huge amount of diagnostics data of 600~900 MB per 10-second short-pulse experiment. It prepares the first plasma experiment in March 1998. The recent increase of the data volume obliged to adopt the fully distributed system structure which uses multiple data transfer paths in parallel and separates all of the computer functions into clients and servers. The fundamental element installed for every diagnostic device consists of two kinds of server computers; the data acquisition PC/Windows NT and the real-time diagnostics control VME/VxWorks. To cope with diversified kinds of both device control channels and diagnostics data, the object-oriented method are utilized wholly for the development of this system. It not only reduces the development burden, but also widen the software portability and flexibility. 100Mbps FDDI-based fast networks will re-integrate the distributed server computers so that they can behave as one virtual macro-machine for users. Network methods applied for the LHD data processing system are completely based on the TCP/IP intemet technology, and it provides the same accessibility to the remote collaborators as local participants can operate.

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