PC-Based CONTROL AND DATA ACQUISITION SYSTEM
H. Mio, H. Amenitsch, W. Leingartner, and P. Laggner
Institute for Biophysics and X-ray Research, Austrian Academy of Sciences
A new PC-based histogramming data collection system for fast readout and on-line
data display of one or more digitising units with the possibility to trigger external
devices will be described. One of the major advantages of the proposed system is
the short intrinsic dead time of only 170 ns which allows a count rate of 1 MHz with
only 0,3 % losses assuming a Poisson distribution of the incident pulses.
Furthermore the graphical Windows software and live display of acquired data
allow an immediate user interaction with the experiment even during an active
acquisition. Since the beamline is dedicated and designed to host a large variety of
scanning and jump-relaxation sample stages (e.g. T-, p-, magnetic field, stopped-
flow etc.) the control system has been developed on a uniform user surface (based
upon LabView) to enable user-friendliness. The main advantage of this user
surface is that the beamline scientist can configure the actual needs for the
experiments based on a great variety of modules. On the other hand the valves,
shutters, the radiation safety system and vacuum pressure interlocks are controlled
via VME-crate and a PLC with network interface to the beamline-PC in order to
guarantee the security for sensible instruments. The experience with the PC-board
and associated software, which has been extensively used at the Austrian SWAX
(small- and wide-angle X-ray scattering)-beamline at Elettra in Trieste during the
last two years, an overview of the acquisition and control system, as well as some
applications of it will be presented.
(posted 22-Oct-97 jw)