SPECTRA is used for a large variety of measurements at the synchrotron radiation laboratory HASYLAB, including X-ray absorption spectroscopy, diffraction, magnetic scattering, powder diffraction, small angle x-ray scattering, standing waves, VUV spectroscopy, etc.
The program controls the beamline components, the monochromator and the diffractometer. It performs data acquisition and monitors the measurements.
SPECTRA runs on OpenVMS (Alpha and VAX) and LynxOS computers. It communicates with the hardware through several bus systems: CAMAC, VME, IEEE-488 and RS232.
The high level user interface of SPECTRA offers features like: Energy scans, q scans, motor scans, adjustment scans, automatic centering procedures, etc. In addition there is an interpreter that accepts input from a command line or command files. The user interface is independent of the operating system and hardware, with the exception of a few commands.
This is achieved by the device library concept: The functionality of the electronic components is separated from the details of the hardware.
New modules are introduced to the software by inserting them into the device list which contains all relevant information about the hardware. The device list is automatically maintained by SPECTRA.
It is possible to run SPECTRA in a simulation mode on those nodes that do not serve as experiment computers.
This note lists only the main issues. The full documentation can be found on a web page [1].