P21 -- A NEW GRAPHICALLY ORIENTED CONTROL PROGRAM FOR
By Juergen Kopf* and Dirk Abeln;
Institut fuer Anorganische und Angewandte Chemie der Universitaet
Hamburg, Martin-Luther-King-Pl. 6, D-20146 Hamburg, Germany.
Two years ago we reported on ''The Application of Graphic Desktop
Software in Single Crystal Diffractometry'' (Abeln, D. and Kopf, J.,
Abstract PS-02.06.01 IUCr XVI, Beijing, China, 1993). In this
report we presented a new diffractometer control program for a
24 years old Hilger & Watts (Y290) rebuild with four
stepper motors. The design goal was to provide a user interface
which is easy to learn and to give a novice user the ability to
collect data effectively while giving the experienced user all
the control necessary to complete difficult tasks. A further goal
was to make the program easily portable for different instruments
and different computers. Therefore, the software including system
software for GEM-calls is completely written in FORTRAN77 and much
attention was paid that the structure of the program is modular
(Abeln, D. PhD Thesis, University of Hamburg, 1995).
By isolating all modifications required to drive a different instrument,
it was possible in between three weeks to re-write the same control
program for an 18 years old, mechanically still reliable SYNTEX P21
diffractometer. This instrument was one of the first diffractometers
where the control software was completely written in FORTRAN. The
computer used at that time was the (now obsolete) Data General NOVA.
Later this computer was replaced by a new ''SIEMENS-interface'' which
simulates the Nova 1200. In contrast to the old-fashioned, 2-letter
command structure given on a VT100 the new control program uses easy
to learn drop-down menus, dialog-, alert- and file-selector-boxes.
The availability of the source code allowed the easy implementation
of crystal-based Psi-angles (Schwarzenbach, D. and Flack, H. D.,
J. Appl. Cryst., 1989, 22, 601) for numerical absorption
corrections with the program ABSPSI (Alcock, N. W. and Marks, P. J.,
J. Appl. Cryst., 1994, 27, 200) and SHELXL93.
Although an ATARI Mega ST2 with 1 Mbyte memory and only 8 MHz processor
speed is completely sufficient even to continously display on-line
profiles of all scan-types for each reflection, a PC version (Linux/X11)
is under development.
For more information, please, send an e-mail message to:
Last changed: 16-Nov-2001. Jürgen Kopf