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 switch.

CIRCE functional diagram. The relative layout and connections between the various parts of the CIRCE Control Hardware are shown.

Hardware Control
Software Control