Instrument mechanical subsystems are controlled through sensors and actuators, and all these mechanisms are
controlled through a computer control system and the control software.
The CIRCE control hardware
consists of four physical units: (1) the cryostat housing the detector array, optics and mechanisms, (2) the detector control
hardware, (3) the mechanism control hardware, and (4) the Local Control Unit (LCU).
The LCU is a Solaris/SPARC rack-mount computer that
resides in the same rack as the mechanism control hardware. It is
connected via TCP/IP over ethernet to a Perle console server, which
provides serial RS-232 lines for commanding device
s such as the mechanism control hardware. All motor indexers and each
one of the monitoring devices are connected to the Perle and accept
commands on a serial line.
The detector control hardware, called Modular
Camera Electronics (MCE), also accepts commands on a serial port
connected to the Perle. The MCE performs the clocking and the readout
of the detector array (Hawaii-2 2Kx2K 1.0-2.5 Ám), the A/D conversion
and the coadding of frames. Once the data acquisition is done, the LCU
receives detector frames from the MCE via a fiberoptic link using the
EDT PCI framegrabber.
Both hardware and software telescope interfaces are
being investigated. From the hardware point of view, the CIRCE control
system is to be connected to the GTC Gbit control LAN via a public
CIRCE functional diagram. The relative layout and connections between the various parts of the CIRCE Control Hardware are shown.