The XMaS beamline is controlled via a Linux workstation (xmas5 running Debian). The user interface is achieved with use of SPEC software that allows several sessions to control the diffractometer in different geometries. Since the EBS restart, the session to run is PSIC (psi-circle, azimuthal reference vector). In order to run the PSIC session, it is necessary to open a terminal window and then simply type the name of the session (in small letters): psic. It is then possible to drive slits and optical elements as well as the diffractometer by using standard SPEC commands. The session also allows the definition of an orientation matrix and subsequent reciprocal space scans.
Two other sessions are used to control the optics and other elements of the beamline: MIRROR and SPECSERV. Generally, these sessions are not needed by the users.
The beamline is controlled through two Linux rackable PCs (ld281 and ld283 running Debian). The PC ld281 in CC1 controls all optical elements, including slit-sets s1 to s4. The PC ld283 in EH1 controls the diffractometer and all other experimental equipment. Device servers are accessed via SPEC or through other ESRF clients, via the Ethernet.
The motor controllers are IcePAPs units, the latest ESRF standard, also directly controlling the encoders. The counting card for detectors is the P201 PC board. Some NIM electronics are also used for the detectors and counters.
Both the vacuum control and personal safety (PSS) systems are hard wired, stand-alone units controlled by PLC's in the CC1 racks. The vacuum control system automatically closes valves in the event of pressure rises, from a leak for example, in a given vacuum section, in order to isolate that section. The PSS enables or disables the opening of the front-end shutter, depending on the status of optics hutch PSS interlocks while the station-shutter is similarly controlled by the status of experimental hutch interlocks. The vacuum control system similarly influences the state of the front-end shutter, i.e. if any valve is closed, the shutter will not open.
The xmas5 workstation also runs several GUI applications that communicate with the vacuum and PSS PLC's. The station-shutter can thus be opened and closed by clicking the appropriate icon with the mouse. Valves can be opened or closed and vacuum gauges read in the same manner.